One key per tour edits money. Settlements, expenses, per diem, crew pay and the budget are edited by whoever holds the tour's money key, plus anyone the holder gives a copy to. It starts with the tour owner, with no copies.
If Money says "View only. [name] edits money on this tour": you can see everything and pull reports, but the save and settle buttons are hidden for you. Ask that person, or the tour owner, to hand you the key or give you a copy.
To hand it on: Money > Settings > Money setup > Who edits money. Tap the person, then Yes, hand it to [name]. You become view only. Who can hand it on: the person who holds it now, the tour owner, or the owner's named designee. Who can receive it: the tour owner, a Tour Manager or an Org Admin on this tour (only those roles edit money; everyone else is view only unless the TM or admin grants them edit). The owner can always take it back the same way.
Copies of the key: for a tour where two people really both work the money (say the TM on the road settles shows while a remote accountant runs the budget and reports), the holder keeps the key and gives the other person a copy. Money > Settings > Money setup > Who edits money > Copies of the key: tap the person, then Yes, give [name] a copy. A copy edits money exactly like the key. Who can give one: the same people who can hand the key on. Who can get one: the tour owner, a Tour Manager, an Org Admin, or a Tour Accountant on this tour. A Tour Accountant normally only views money; a copy (the TM or admin signing off) lets them edit it on that tour only, the same as the key holder (adding, changing and deleting money records, all in Activity and undoable), but never expense approvals and never on any other tour. Take back removes a copy at any time, and a copy holder can Give up my copy. Copies stay when the key changes hands. A copy goes away when that person leaves or is taken off the tour, or moves to a role that can't hold one (like Management); adding them back never brings it back, the holder has to give a new copy. Every change anyone makes, with the key or a copy, is in the tour's Activity log under their name, so you can always see who changed what.
Production Manager: a Production Manager sees nothing of Money on their own. The key holder, the tour owner or the designee can give them a copy (Money > Settings > Money setup > Who edits money > Copies of the key); the copy opens Money to them on that tour only, to see and edit, never Money admin and never the key itself. Taking the copy back closes Money to them again. If the tour's admin set this person's Money in People and access, that choice wins over the copy.
History: under the hand-over, History lists every time the money key changed hands on this tour: who it went to, who handed it over, and when (newest first, last 20). It also notes when someone holding it left the tour and it went back to the owner or the designee, and every copy given, taken back or given up. Anyone who can open Money can see it.
Every hand-over is recorded in the tour's ownership history.