Question around Journal Reversal

Hello,

I would like to know:

1) when you add a new journal reversal set to a Secondary ledger, will this apply to journals already created in the Secondary ledger before this set up? Or does this only apply to journals created since the criteria set?

2) Lets say you do already have a journal reversal set configured, when you add a new category to a journal entry reversal set, will this apply to journals already created?

3) If you open a period which has already been opened, will this apply a auto reversal if the configuration is set to autoreverse upon opening a period? Or does it only apply to new period being opened?