Hi all, recently i’ve install on my laptop endeavouros and it’s a very pleasure to use it at work. I choose the gnome DE for the desktop. But i’ve a problem with the personnalisation; yesterday i’ve downloaded a theme on the gnome look’s website. The folder is copied on /usr/share/themes and /home/x/.themes but when i select it with the gnome tweak tools, the theme is dont apply to all gnome app. If someone have a solution for this problem, tell me the way to solve it.
Thanks more
Hey there! 
It’s awesome that you’re enjoying EndeavourOS on your laptop – it’s a fantastic choice!
Now, let’s tackle that theme issue. It sounds like you’ve got the right idea by copying the theme to both /usr/share/themes and /home/x/.themes. But, sometimes GNOME can be a bit finicky with its theming.
First off, make sure the theme you downloaded is compatible with your GNOME version. Outdated or incompatible themes can cause hiccups.
Now, if you’ve already done that and it’s still not playing nice, here’s a trick: open the terminal and try running gnome-extensions disable followed by gnome-extensions enable. This can sometimes give GNOME the nudge it needs to apply the theme consistently.
If that doesn’t do the trick, you might want to check if there are any specific instructions that came with the theme regarding installation. Some themes have extra steps like tweaking settings or installing additional dependencies.
And lastly, don’t forget to restart GNOME Shell after applying the theme. You can do this by pressing Alt + F2, then type r and hit Enter.
Give these a shot, and hopefully, your GNOME desktop will be looking snazzy in no time! 
If the issue persists, feel free to drop more details here, and we’ll dig deeper into the troubleshooting rabbit hole. Good luck! 
by default GNOME is using libadwaita traditional way to use themes like in gtk before is not working anymore… you can still apply theming changes but needs something like this:
There are some extensions that can help color scheming
Gradience
but still partly only an idea… if you are using apps based on gtk2 or 3 … they will not follow … qt app? will not follow…
“legacy” apps will need to set theme in tweaks tool where it takes themes you saved in theme folder at users home …