In messing with my 255 many months ago, I managed to add what I think is a custom HIIT session, but none of it makes sense to me as it looks like a simple count-up timer with zero functionality. I've tried to restore this activity to its defaults and have removed it from my favorites, but now when I chose this activity, I see none of the pre-defined HIIT options that are described in the manual and shown on all of the tutorial vids I've seen. I really don't want to do a hard reset on my watch and set up other customizations. How can I get the original garmin HIIT functions back?