Before you begin, read this:
For example, Bebo Akapane and Komppi share a flag. The flag in question is g+15.
To use it, find "Tools" (on top of the program), then find "Expressions". You'll be taken to a separate window. Find gender and set the default to 15. To make the flags work, make sure the resampler is set from WORLDLINE to CLASSIC.
You can change the number to use on different characters. Sadly, you can't use different flags on two different voicebanks at the same time (yet)