I seem to remember that in the past, if one enters a transaction in a register and does not enter a category, there was a switch that informed Q to remind/double-check that you wish not to have one included in the saved transaction.
I don't see that as an option now in my QFW R65.29 on Win 11.
Am I imagining this existed in past years...and if not, does anyone know where the toggle is nowadays. I've gone through many setup panels trying to find out.