My sisters friend signed her HBO max account into my parents living room tv under their roku account. On a completely different tv and different roku stick I have my own hbo max account and somehow my sisters friends HBO account showed up on my tv and got rid of my hbo account ?? Any ideas
If Roku devices share the same Roku account the HBO max channel will sync to all the devices. Just log in and log in and switch the account by logging out. Here is helpful link
https://streamersworld.com/roku-how-to-sign-out-of-hbo-max/#Signing_Out_of_HBO_Max_from_the_Channel
I don't have HBO so I'm flying blind on this, but ...
There should be somewhere within the HBO app where you can log out of the current HBO account. Look for it under something labeled "Settings", "Account", "Options", or similar, or maybe just an icon looking like a gear or a head profile.
Once logged out, then you should be able to log back in, this time using your own account login parameters.