How do I Hold a Variable value

I have some variables in the First layout to deal with the volumes. They are all = 0.

If I change this variables to 1 and go to the Second layout, they still 1, but when I come back to the First layout they automatically change to 0 again.

Every time I enter in the First layout the variables are set to 0... and this is not made by my code. How to hold their value?

It will be an issue in the code. Assuming they are global vars you will be setting it to 0 with some event linked to the first layout.