In Meta Ads, on the Ads tab:

  1. Turn on Bulk edits and select the ads.
  2. Open the name editor.
  3. In the Change Ad Complement only box, type the New Ad Complement and click Apply.

It keeps the beginning of each name and replaces everything after the first " - ". Example: "VID01 - Black Friday" with the Ad Complement "Christmas" becomes "VID01 - Christmas". Leaving the field empty removes the Ad Complement. Click Save to apply the changes: the new names show up in the table right away.