If this is a repository project you should be able to undo your changes.
If not then you can edit the interview.xint file in your project directory, find <screen Title="" ... and insert your required title. Direct editing of project files is not normally recommended but there doesn't seem to be a way to do this in OPM although I may be proved wrong on this.
Here's a much easier way to do it in OPM:
1. In the Interview tab, click on the screen icon in the left panel.
2. Press F2.
3. Voila! You can now type a name for your screen.
I worked this out myself when I accidentally deleted a screen name. F2 is the generic shortcut key for renaming a file (e.g. in Windows Explorer), so it seemed a good guess.
Hi Ian, Jasmine,
Thank you both so much for replying! I shall definitely try the slightly easier option going forward. Fortunately I had most of the interviews in Controls so did the manual drag and drop to get what I was after as I was short on time for a demo.