Have you made sure the issue is not that the TV itself is zoomed in too far for the Roku image to fit on the screen? Various TV manufacturers have different names for this function. Look for labels like Zoom, Size, Picture, or similar.
Many TVs store this setting separately for each of the TV's inputs.
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.
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Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X