Rongway already gave the example but I'll add up abit.
In my case, I always swap one button to match each encounter needed (Interject for O3S, Lowblow for dungeon, Shirk for Ex/else), my macro is like this.

/mlock
/micon Shirk
/e Changing actions ........
/aaction Low Blow off
/aaction Interject off
/aaction Shirk on
/hotbar action "Shirk" 3 12
/e <se.7> Ready!

then swap Shirk with above two for other two macros.