How to Move ‘Min, Max, Close’ Window Buttons to Left on Ubuntu 21.04 (Hirsute Hippo)
The easiest way to move the window buttons in my opinion is to use gnome tweaks
1. Open Terminal (Ctrl + Alt + T) and run his command
sudo apt-get update
sudo apt-get install gnome-tweaks
2. press alt+f2
type gnome-tweaks and press enter
3. After gnome-tweaks window pop up, click to Window titlebar tab.
4. After that you can move the toggle button to the left (or right) Window placement.