My back up disk for time machine suddenly says it read only. It won't allow me to change it.

kimbruder wrote:

I recently purchased a new Mac Air. Since reconnecting my Seagate external back up drive for time machine suddenly says it is read only & cannot back up. I tried changing permissions & it won't allow me to change it.

https://discussions.apple.com/content/attachment/eb8e042a-64a9-4de6-b930-1b3e3304ccf0

It says I do not have permission?

Was the old Time Machine encrypted...?

You can reformat the drive and start a new backup if no resolve.

Erase and reformat a storage device in Disk Utility on Mac

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

see Time Machine and enclosed links

Types of disks you can use with Time Machine on Mac - Apple Support

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

If your drive is a dedicated Time machine drive it will always show read only running Monterey. If you want to write to that drive yourself you would need to partition the drive which I do not recommend.