do I EDIT the devices in existing scene?

Hi all…ive had user created scenes for my arlo cameras for years, but wish to add a new camera to a particular scene.(so a camera turns on when a scene is run )
Ive tried everything but can not see how to EDIT the devices in an existing scene…only delete or rename
anyone got a clue how to do this?

if you tap Edit, do you see the Add Action on the screen?

Yes I get add action, which then takes me to a selection screen…however it does NOT show devices already part of that scene. (It does allow me to add what should already be there)
What I HAVE found is that if I add a NEW scene, and set up the same actions , then I can edit that fully , so it seems it doesnt pick up what devices were assigned to an existing scene (pre new app)
For ease I think I will redo my scenes from scratch to make sure they are all current - there are only 5 important ones
Yes, just confirmed if I ADD what should have been there in an old scene, it now is editable
Many thanks ! …that was the clue I needed