USB mouse extra side button

USB mouse extra 2 side button not working. How can I enable these buttons?

What are they used for? By default I think they navigate back and forward in a browser.
Does this not work for you?

Yes they are back and forth buttons. They are not working for some reason. Is there a way to make it work?

My forward back buttons are working out of the box.
But if your’s do not, or you have even more buttons you need to map, then there is three options I know of:
A: edit your ~/.xbindkeysrc file manually
B: Right click your Desktop->Desktop Settings->Mouse Actions
C: Install and use easystroke

However, since you just recently installed your system, you may try updating it fist, if you haven’t already.
Could’ve been a bug that was recently fixed.