The most abilities a single character can have is about 30. each bar gives 12
12 X 4 = 48 - 12 for your companion's bar = 36 you should be able to have at least 6 slots open to put in clickable items like Throw Huttball, Use Medpac, and use Relic activation.
If you don't know how to access these last two bars it is quite simple.
LOOOK AT THE OPTIONS MENU YOU FIG NEWTON.