Offline images

I have looked at the CO info on offline images . However, I'm not at all technical so I may have overlooked the info I'm seeking. I have 70 catalogs most of them offline. Originally they were all locked: read only, but this issue has been solved. Possibly in solving the "locked" issue I have created the "offline" problem. I transferred the images on my original external HD to another external HD, erased the initial HD, renamed it  "Photo Masters 31 March 21 and transferred the images back - this unlocked my catalogs. 

Looking at Disk Utility (see screen shot) seems like a nightmare to me. I have the two "G" 10TB HD's and a LaCie Rikiki running a CCC backup. I attached a laCie 5TB and 3TB to take data when erasing my "G" drive...

In the "New Plymouth..." catalog (see screen shot) all the images have the question mark - I changed the folder (highlighted in orange) from Photo Masters Two (original folder) to Photo Masters 31 March 21 (new folder), but images still offline.  

Would be very grateful for help with this......