The agreed total
A booking’s quote is worked out from your rate card every time you look at it, so it moves when your prices do. The agreed total does not: it is what somebody said yes to, written down.
Confirming a booking agrees the quoted figure automatically — but only when it can actually be worked out. If a price is missing, or you haven’t recorded how many are coming, nothing is agreed and the booking says so. That is deliberate: a total of nothing is not the same as a booking that costs nothing, and freezing the first as the second is how a group ends up looking paid up when they have not paid at all.
You can type your own figure at any time — a discount, or a price agreed on the phone — and it wins over the rate card. If your prices later change, the booking keeps its agreed total and tells you the two no longer match, rather than quietly moving what the group owes.