Try this:
Once on Disney+ home page on your Roku, click cursor-down once to activate menu on left side of page. Click on SETTINGS at bottom of menu.
On the Settings page, click on Log Out.
Page will be replaced with a SIGN UP NOW / LOG IN page.
Click on LOG IN. Sign in with YOUR Disney+ account credentials.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X