Normally, shooter scores are calculated and saved when you click OK after entering data.

 

You can force the match to be recalculated if you need to.  The only times I've needed to have been after changing the size of a match after some scores had been entered.

 

This is NOT the same as dropping a stage from a match - that will normally recalculate automatically.

 

Hold down Ctrl and Shift and Alt and then tap the C key (as in "calculate").