@Sagord
Try plugging your Streaming Stick into the wall outlet rather than your TV's USB port. This will stop the Streaming Stick from powering down completely when you turn off your TV.
Your Streaming Stick will now enter a Sleep Mode rather than powering down/rebooting. Just press Home on your Roku remote to "wake" up the Streaming Stick after turning on your TV.
If your Streaming Stick did not come with a wall adapter, try using a cell phone charger USB adapter (5volt, 1 amp).
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102