How can I set that I’m not currently on my device and the tower sees it and I can just keep flying?
While I’m not sure how to set the away mode, I’m pretty sure you can only set that away mode when you’re in center/director airspace.
First of all, welcome to this amazing community! I hope you’ll enjoy it, have some fun, and last but not least, learn a lot of things. :)
If you’re flying through the airspace of the Tower controller, you should be at your device, since that’s often during take-off/arrival. If you, however, are thinking during cruise, and in regards to Center controllers, you will get a status as being “Away” after a few minutes of inactivity. That means the controller is aware that you’re not at your device, and nothing should happen to you.
It is however always recommended to be at your device during climb, descent and landing.
Adding on from what was mentioned above, if you are within Tower or Approach airspace then you must follow all ATC instructions at all times.
If you are at cruise and flying through Center airspace then if you do not touch your device for a few minutes it will automatically set your status as “away” and ATC can see this from their end. If your status is away, ATC will assume any collisions are unintentional and you will not be reported for it.
Hope this clears things up. Take care!