How do create a global save variable?

I have a game created with 3 different levels on a different account. At the moment, I have followed a tutorial on local save storage, however, this is not what I looking for. I am looking for global save storage in specific and I want to save scores between 2 layouts.

I don't understand your question. Global variables are not reset between layouts. So if you save a score in a global variable and then switch to another layout, the score will still be there.

Or are you asking about sharing data between two different games (two different projects)?

Would it only reset if you tell the variable to reset?

Yes, if you use "Reset global variables" action.