In the Surgery Search screen, there is a function called "Bulk Operations" in the left side column, under the "Search" and "Clear" buttons.  To change the status of multiple surgeries, ie. from "Upcoming" to "Done":

1. Run a search on all "Upcoming" surgeries 

2. Select the surgeries to be changed to "Done" (by clicking on the checkbox on the left hand side next to each patient/surgery)

3. Select "Done" from the dropdown in "Bulk Operations"

4. Select "Yes" to the prompt of whether you want to change the status