Here's another one then: in heliboard settings, go to about, and hit "Description of hidden features." It's where I found that, plus a few more neat tricks!
Honestly, I just found the android app incredibly clunky and annoying to navigate. I'm hoping it'll improve with time, because I would like to move to a FOSS solution.
I'm in the exact same boat. If someone figures out how to get tap-to-pay working on graphene, I'll be daily driving it so fast.