I think it's normal that you can't edit the "Global User". You need to have at least one user.
To change the password of this user, you should use the command
runuser -u _gvm -- gvmd --user=youruser --new-password=yournewpass

For the other users you can edit them and change the passwords.

You have deleted the global user and it seems you can't create a new one. Can you check the log after you run
runuser -u _gvm -- gvmd --create-user=yournewuser --password=yourpassword
In /var/log/gvm/gvmd.log

Year.I create a new user,and it would create a new passwd by itself.It look like my passwd is not valid .

I try to login by webui,and it can't login by my passwd.But I can login again when I modified the passwd again after I run
runuser -u _gvm -- gvmd --create-user=yournewuser --password=yourpassword

I check the log and it had nothing error in it.

I login the webui,I only found a user in it ,and I only found a user whose role is admin but I can't modidy it.
I used another account to login again,and it's the same as the before.It tell me "Permission to edit user denied"

image-4.png (105,575 bytes)   

image-4.png (105,575 bytes)   

image-5.png (21,712 bytes)   

image-5.png (21,712 bytes)   

This report has been filed against an old version of Kali. We will be closing this ticket due to inactivity.
Please could you see if you are able to replicate this issue with the latest version of Kali Linux (https://www.kali.org/get-kali/)?
If you are still facing the same problem, feel free to re-open the ticket. If you choose to do this, could you provide more information to the issue you are facing, and also give information about your setup?
For more information, please read: https://kali.training/topic/filing-a-good-bug-report/