definition only shows when flexing a muscle
hope this helps
You have much to learn.
Biceps should be flexed in every pic. A thumbs up is most often used to get the arm in the most flattering position. Keep a straight face though - because you are flexing but need to make it look as if your arms look like that relaxed.
This is all pictures - snaps out with friends, childrens birthday parties, close to death in hospital, weddings and of course funerals.