Transaction issue. Global change?

Yes, although still tricky - since you don't want to change all transactions that are “Restaurants and Bars” back to Groceries… you'll have to have an idea of which Payees were for groceries.

Batch change tip thanks to @jacobs who helped me out with this issue recently…

1. Click on Banking in the left list of accounts to get a register view of all transactions from all bank and credit card accounts.
2. Click the small ‘v’ next to the search magnifying glass at the top right of the screen and select Category to limit the search. Then type in Restaurants and Bars and verify that only transactions with that category are now in the list.
3. Sort the list by Payee…. click the Payee heading.
4. When you find a group of transactions for a payee that should be categorized as Groceries, click the first one, then shift click the last one to select them all… and finally either press cmd-I or menu File > Get Info (belongs in the Transactions menu, but that's another story).
5. Type Groceries in the Category field, replacing Restaurants… the checkbox in front will automatically be checked. Press OK and those transactions will be recategorized and disappear from your filtered list.
6. Repeat until done.

As @jacobs and others have noted, a severe shortcoming of this batch change feature is that it will not change splits in split transactions. So, if you had a grocery store purchase that was split between Groceries and Pharmacy/Drugs, Household or whatever… it will not find or change those.