Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
I realize this is a slightly old question, but for anyone coming in from the CBS or Paramount+ channels: If you pause long enough for the screensaver to come up, the channel gives this error when you unpause. Like a baby seeing their dad after a haircut, it thinks you're a new person, so it's telling you that someone else (you) is already watching.
You don't need to delete anything or change your password. Just click the Home button to go to the Roku homepage (with your channels on it), re-enter CBS/Paramount+, and resume your show.
If you're going to be away from the TV for a few minutes, instead of hitting pause, hit the Back arrow to the home screen for the TV show you're watching. No video playing = no 'concurrent stream' issue.