I have a new Kobo. I had previously authorised my old Kobo to Digital Editions & could read books from the library. I cannot authorise my new Kobo. In settings it shows under adobe authorisation "not signed in".In adobe Digital Editions it shows "this computer is already authorised". How do I authorise my new Kobo to Digital Editions?
I'm a bit unsure exactly what you are asking, so a couple of questions and tentative suggestions.
Is this a Kobo tablet (which is usually authorized within the tablet app) or an ereader (which is usually authorized from ADE on a PC)?
In adobe Digital Editions it shows "this computer is already authorised"
Presumably the computer was authorised already, so there is no need to authorize it again.
If the Kobo is an eReader device, you should be trying 'Authorize Device', not 'Authorize Computer'.
I assume you only have one AdobeID? If you are trying to use a different one on you new Kobe, that will cause problems.