My PS3 controllers are pressing random buttons

You could take them apart and clean the controllers and you may have bumped the motherboard out of place making it sometimes hit random buttons. If after cleaning and making sure everything is put back properly and it still does it you may have to get new ones or go buy used controllers at a store or online.

Buy a new controller

You can either:

A) Clean the button membranes with the help of this guide: Button Replacement Guide

B) Use a paperclip to press the small reset button on the back of the controller located on the top right of the label

C) Follow this video if the previous options don’t work.

If none of the solutions work, then I suggest taking them to a repair center or buying new ones. Hope this helps!