The back buttons don’t work on my remote. Example: on Hulu, if I go to My Stuff in the menu, the only way I can get back to the main menu is to go all the way back to my Roku home page, select Hulu and start again. It’s the same with Netflix, prime and all other. Advice?
These things are just special purpose computers. I don't know if this will help with your particular problem, but like their big brothers, sometimes clearing things out by restarting them can correct problems.
Depending on your Roku model you'll find the "System restart" under "Settings > System > Power", or if you have no Power option, under "Settings > System".
If a restart doesn't do it, or if you don't have sufficient control with the remote to navigate the Roku menus, you can also restart by pulling the power plug to the Roku for a minute or so then plugging it back in.