Anyone know how to switch RR3 to a different Facebook account on Android?

I know I must have found a way to do this in the past, as I did this on my tablet. But I want to play occasionally on my phone, and can't for the life of me work out how to do it.

I use a different account for RR3, not my usual personal account. But I cannot work out how to get RR3 to prompt for a login.

I guess I could switch accounts temporarily on the phone itself, but it'd be nice to find a way to do it in RR3.

Hugh Mercury (for RR3 purposes!)