Thank you for your reply.
How would I 'look under the hood' exactly? Sorry if that sounds a little dumb, but in an os like windows, that kind of stuff doesn't happen. Is there like a console you can view, or some code you can look through and fix or something? How would I start doing this for example and how experienced with unix and C would I need to be to do this?
Sorry in advance for the TL;DR!
Other than a few proprietary, binary blobs in the kernel (usually drivers for hardware that certain vendors do not want to publicly disclose the source code for); Almost every software component available in Linux based OSes are free/libre software and have source code available. Most distros do include some non-free software. There are some distros like the GNU/FSF approved distro Trisquel, which remove ALL non-free software. Either way with very few exceptions, the source code is available for pretty much every single piece of software in any given Linux distro.
Where you actually get the source code from would depend on which distro you have installed. Usually the source code is in a separate repository that you have to enable in your package manager. Then you can use your distros package management system to download the source code for whatever packages you want and you can peruse it at your leisure. Otherwise, you could go to the website for the original developers of the software and get the source code directly from them. Either as a zip or tarball from their downloads page, or from their version control systems (git, svn, bazaar etc).
In order to understand the source code, you'd need to be a proficient programmer. But the implementation language used isn't necessarily always going to be C or C++. The Linux Kernel itself is written in C, but other software on the system could be written in C, C++, Lisp, Perl, Python, Haskell, Shell-scripts, or any number of other programming languages.
For example, the Gnome desktop is written in C, KDE software is written in C++, the XMonad desktop is written in Haskell, I think Emacs is written in Lisp (or it might be a combination of C and Lisp).... Either way, whichever piece of software you want to check out the source code for, it helps if you have a good grasp of whatever programming language was used to implement it!
But ultimately, you don't have to be a programmer in order to customise your Linux installation:
If you have a car, but you aren't a mechanic; you can still look under the hood of your car and should be able to fill the washer reservoir, top up the oil, check the coolant and transmission fluid, perhaps change the oil, or clean/replace the air-filter, check the fuses in the fuse-box, change bulbs etc.
Likewise, if you aren't a programmer, there are things you can do under the hood of your OS without really having to understand source code, or do anything too technical.
As an example:
With M$ and Apple OSes, you only have the one desktop environment. The amount of customisations you can make are extremely limited. With these OSes you are constrained to work in certain ways. Sometimes you might find that the OS makes it difficult to do exactly what you want without jumping through hoops, or you are unable to get things to look and behave the way YOU want them to. And that is the important thing: making your computer work for you, rather than you working for it! Once you've exhausted your customisation options in Windows, what do you do? You're stuck, right?!
One of the great things about Linux is that there are many different desktop environments and window managers available. All are customisable and configurable to differing extents. Most are far more flexible, configurable and customisable than their proprietary cousins.
So if you install a Linux distro, you like the way it runs on your system; but you don't like their default choice of desktop. You can either try to tweak the settings of that environment to suit your needs (as you would in Windows or OSX). Or you could install a different desktop. One that you CAN customise to look and feel exactly the way you want it to. And you don't have to remove the old desktop environment either. With Linux, you can install multiple desktop environments alongside each other. When there are multiple desktop environments installed, you can choose which desktop session to log into at the login screen.
With Linux, you can make your entire environment fit in with your preferred workflow, rather than having force yourself to use whatever paradigm a committee in the boardroom of some multinational corporation somewhere came up with. And all without looking at a single line of source code!
Granted, you might have to type in a few commands in the terminal in order to install a different desktop using a command-line package manager. But again, in most modern Linux distros, you don't have to go anywhere near the command line if you don't want to. You can just as easily install a new desktop using one of the GUI based package management systems like Ubuntu's 'Software Centre'.
So completely changing the desktop environment is a very simple example of something that you can do 'under the hood' to improve your user experience in Linux that you couldn't do in Windows. And it's not just the desktop you can change. You could change the login screen/login manager, the boot splash-screen image/animation. If you don't like bash (the default command-line/shell on pretty much all Linux distros) you can switch to zsh or ksh or any number of other shells that are available. Whereas on Windows, terminal-wise - you're stuck with cmd or powershell.... Unless you install Cygwin that is!
At the end of the day, if you don't like something on Linux; you have the freedom to change it, either by editing the source (or applying a patch from somebody else) or by replacing it with something else. Whereas with other proprietary OSes, you're pretty much stuck with what you've been given and just have to live with it.
IMO, other than zero cost, the main advantages of Linux over other OSes are freedom and choice. And I'm not just referring to the freedoms granted in the GPL, but the freedom offered by the vast range of free software that is available to you.
The portability of the kernel and other free software also gives the advantage of flexibility. You can install a Linux based OS on pretty much any device and in any number of different configurations. Be it an embedded device/simple state-machine (like an ATM or a washing machine), a robot, a drone, a phone (see Android and Ubuntu phones), a tablet, a laptop, a desktop PC, or a supercomputer/cluster. It can be used as a server, a router, a thin client, a web-kiosk/display etc.... So many uses.... Can you honestly say that about any other OS?
