Customizing data screens for a workout

Hi all! in my 255 I have created a customized workout as follows (just to make an example):

- 300 meters running

- 3 minutes recovery

When a start the workout the data screen appearing on the watch is (don't believe the data, it's just an example!!):

How can I change the data field? as example, HR instead of time (0:46)

And for the 3 minutes recovery the screen appears as follows:

Where upper numbers are too small (2:39)

Do you know where can I change both data screens? I have checked in Data screens but this screens do not appear in the list of all available data screens.

Thanks