That is normally the default. Are you selecting something in the message you are replying to and getting only the selected text perhaps.

Otherwise there is a setting in account settings > Composition and addressing to automatically quote the original message when replying.

Thank you Matt. I probably highlighted something and that caused the reply to just include what I highlighted. Now if I can just find my address book after installing (bad choice) ver. 91.0.3!!! I didn't realize that I was installing a new version. I feel that should have been highlighted. Thanks for your help.

The address book has not moved. Have you migrated your profile from whatever was the old device?

Hi (again) Matt - No, I haven't migrated anything. I was on ver. 89 on my laptop (WIN7) when it hiccuped and I started moving everything to my Dell desktop (WIN10) and when I first checked my e-mail I was informed that a new version was available. As always, I immediately "did it"! I didn't realize that I was going to screw up the entire world. Now I'm trying to save my world. DETAILED instructions need to be provided for people that are not computer experts. Sometimes I think the problem with "open source" software is that too many people have their fingers in the pie. Thanks for your help.