How can I set all mail in inbox as unread?

[Merrilee]

After I read email, it isn;t showing as opened. I tried to change it so it
owuld and inadvertently changed all emails to show as opened. How do I
switch it back.

My computer was stoeln (with no backup) and trying to recreate what I had
before is a REAL challenge!

 

[Roady [MVP]]

You can select the messages which you want to mark as unread again and then
use Edit-> Mark as Unread or press CTRL+U.