In Finder & in column mode, highlighting a file does not provide information on or a image of the file in the space to the right.

I need to add that after having sent the above reply, I realised I was following your suggestion without first clicking on a file. I corrected that a moment ago and found it was so simple a solution. And to think I spent an hour on the phone with Apple's advisor. I should have come here first.Next time I will. Just want to thank you again. You've been a big help to me. Thank you again for your help.

I followed your advice & clicked command, shift & p & got a an error sound. I rebooted, but got the same result.

To answer your other question re Safe Mode, I did this at the advisor's suggestion & it worked fine. During startup just now I noticed 2 images, the usual one & the other labeled Test left over from my session with the Apple advisor. I tried entering Test, but could not replicate the password.

Thanks for your help. Any further suggestions would be much appreciated.