If the original source material was produced in 4:3, it likely is still being presented in 4:3, perhaps with black bars on left and right to fill it out to 16:9. What specific program(s) are in question?
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