If that is a screenshot you made, first off you're likely not using ubuntu, but some derivative like lubuntu or w/e.
Isn't that some outdated attempt to boot and run a linux distro on a chromebook without removing or hurting chromeOS? That seems like a pretty bad place to judge ubuntu. You know what? If you can install windows 10 on an android phone and it works better, notify me and i'll move back to windows permanently.
>i cant find any way to open software sources anywhere
You can usually edit sources from your package manager ("software", "discover", "synaptic" or whichever you have), or just using the terminalhttps://help.ubuntu.com/community/Repositories/CommandLine
`sudo nano /etc/apt/sources.list` to open it and add/change sources. Make sure you understand what you're doing before you do it, Google can further help you.
Also keep in mind that the primary source of software for linux distros isn't ppas, flatpaks or snaps. Every distro has its own software repositories, and you can install things from there.
>i cant open any exe files
LMAO what were you expecting? Windows can't run anything from linux but you expect it to work the other way around? The fact that wine exists and can run games like league and software like ms office simply means that linux is miles ahead in this aspect. What does windows have? A fucking bash emulator.
If you don't have a dedicated machine for doing linux and must use it on your school chromebook, just consider finding some student job until you earn enough to buy some used laptop. If you do have a machine, dual boot it with whatever else. And ffs use stock ubuntu before you try alternatives so you at least know what 90% of the posts you read on google are about.