The PBS app on Roku currently can't record where you are in a video while a video is playing. Because of this, when you leave the video or the PBS app while a video is playing, the app won't be able to remember where you were in that video, and the video will not be listed in your account's Viewing History. If you return to that video, you also may not have the option to resume the video from where you left off, and can only start the video at the beginning.
As a workaround, you can pause a video before exiting the video, leaving the PBS app, or turning off your Roku. By pausing the video, our Roku app can record the video in your Viewing History, along with how far you were into the video at the time of the pause.
We are planning to update our Roku app in the near future so that the app is better able to remember which videos you have watched and where you are in those videos without the need to pause a video before you exit.