Help me please, global variable

I want to have an application who can tracking my expenses on a monthly basis

I have a google sheet with column month, year, salary (november, 2020, 1500€)
I have a google sheet Category with column description (ex: food, car fuel, car insurance, mortgage loan…)
I have a google sheet Transaction with column month, description, amount (ex: november, Gazoil, 50€, etc…)

I want at startup of the application, to choose or encode new month, year, salary.
And after, when I encode my transactions… each transaction refer the same month

When I change the month on startup, new transactions refer the new month…

I don’t see how to do that without encode the month in the same time I encore the transaction…

Is there a way to have a global value I can reffer when I want ?

Thank for you help

If I understand this right, you can write that to a column in the data using a text entry/choice component.

Then in the form, have the default value for the month point to the column above. Would it work?

If i understand you, yes … i must choose a month each time I insert a row with help of the form

I want not to choose the month each time