Q: image titles

Photos does not have this batch change option. You can select all photos in the album at once, open the Info panel with ⌘I,  and enter the same title for all photos in the album in the title field of the Info panel.

If you want to add padded numbers to the title use one of the scripts from the User Tip section: Photos for Mac

• Photos for Mac: Batch Change Title to Capture Date-Description-Padded Sequential Number
• Photos for Mac - Batch Change Title to Text w/Padded Sequential No.

Roy, the title field is the second section  of the Info panel for the selected photos.  Have the album selected orr the photos in the album? Select the photos by selecting the first photo in the album and then pressing ⌘A . Now enter ⌘I to open the Info panel. Close it, if it was already open and open it again.

It should look like this.

Also, enable all Metadata in the View menu:  View > Metadata > Titles

MacBook Air, OS X Yosemite (10.10.4)

I just looked at your profile signature. Are you still using Yosemite?

The ability to batch edit several photos at once has been added with MacOS X 10.11. If you did not yet update to E lCapitan, you cannot batch change photos.

You're welcome, Roy.