How to change budget amount?

[Bingbong26]

How do I change the amount allocated to a particular budget item for a given month? Say I want to set my monthly budget for groceries to $800 bc of inflation, how do I go about setting that?

Do I have to transact money from an account and credit it/transfer it to my grocery budget line item?

If it helps, my current mindset is that of every dollar app.

Thank you in advance