How can I priorize one macro?

You should add your ACTIONs in each Macro.
For Macro X:

Of course. The "Notifications" were just my test actions.

No such think as a stupid question. Do your homework, do your research, do your testing, and feel free to ask any related question.

Maybe this will help:

Getting Started with Keyboard Maestro

For more help, see Getting Started with Keyboard Maestro and the Forum .