Why do I see large numbers counting down on the screen as I leave a green?

It's possible you have Big Numbers mode enabled during play. You can disable that here: 

Thanks, but no. I think I've figured it out. There appears to be a count timer that begins when you leave a green. Shows you the seconds since you left. Switches over to "enter score"when you reach the next tee.

Not sure why the timer is there. It doesn't seem to add any functionality as far as I can see.

I haven't seen that before when keeping score on an Approach S50. Is it possible that you have a countdown timer running in the background? See: Starting the Countdown Timer

If you happen to see it again, please try taking a video and let us know. That will help us identify what it is that you're seeing. You can upload that video using our Secure File Upload process as described here: Sending a File, Folder, Photo, or Video to Garmin Product Support

This has happened to me also. I can't figure it out. Using a Venu x1