I can't get time Machine to select disk for backup. It seems frozen.

That app is part of the OS. You would have to reinstall the whole OS but I doubt that is the issue. What disk do you have and is it formatted correctly? Does it show up on the desk top?

Back up your Mac with Time Machine - Apple Support

You're most welcome.

see > Keep your Time Machine backup disk for Mac secure - Apple Support

and > Choose a backup disk and set encryption options on Mac - Apple Support

Personally I do not encrypt our Time Machine or other Backup drives. However it is a good idea, if you are gone a lot, have kids with flaky friends or have any other shady types hanging around with easy access to your Mac and backup drives.

It's not the external disk - it's Time Machine itself. I see images online of people being able to access external drives through TM including adding, deleting old, etc. My TM doesn't pull up that option. This is all it will give me. And when I click on the red "i" it just says "disk cannot be found". So I can't anything new or delete anything old. I can't scroll down on the screen at all, trust me I've tried.

I'm having a similar issue. There is no way for me delete old drives as there is no option to "Add, delete, etc". It just shows my old, old drives with a red "i" next to it but there is no way for me to delete these.

OMG! I was using a trackpad so I used a mouse instead and it worked! THANK YOU! You're awesome. One last question - when I start to back up my new Seagate disk it says "you're backing up an encrypted disk to an unencrypted disk". Any suggestions? Thanks again!

It may just be hidden by the number of backup drives that you have added.

Try scrolling down in the list of drives to see Add or Remove Backup Disk....

There is no scroll bar. Try hovering your pointer over the drive list section and scroll up/down.

Erase and reformat drive to APFS GUID Partition using Disk Utilities and try again with TM

Thank you but that's the problem - it's impossible to scroll anywhere. There is no scroll bar and I've tried clicking on the screen and trying to scroll. Any suggestions?

Not sure if my last response went through but I have tried to hover and hover/click and nothing. Sigh.

With what input device, a mouse or trackpad?

You're awesome (again). You have solved something that has been driving me crazy for a looooong time! :)