My catalogue for elements is on drive C.
My pictures are on drive D: but want to replace them on drive E.
How to do it (Windows 10).
Start by creating a new master folder or named folders on your E drive. In the Organizer left-hand panel choose Folders and select tree view – see image below. You can then select files and use the move command.
You could test this with a single folder before moving everything in bulk. Choose a folder on you C drive and select the first thumbnail. Press Ctrl+ A or Cmd+ A to select all. Then go to the menu and choose File >> Move
Click the browse button and choose a location on your E drive to move the selected files into.
You may also wish to amend the location for future saved files. From the Organizer menu go to Edit >> Preferences >> Files and change the location for saved files.