Hi, I've an issue in my couselab module development! I'm trying to declate a global variable on one slide but i can't access it on onother slide. I don't know how to do this! Please, help.

You need to set this from the drop down menus. You want to open the Module runtime settings. You can define global variables there.
Or you can set a variable at the page level, you do then need to define if these are just page level or global in scope.