If it's happening on a bunch of channels, see if a system restart fixes it.
Depending on your Roku model and Roku version number you'll find the System restart option under either Settings > System or Settings > System > Power
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 device for a minute or so then plugging it back in.
If the problem continues, while watching a program pull the remote's batteries and leave them out for a while. Does it rewind while the batteries are out?
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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Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X