How to change encrypted dmg password

I created a brand new dmg file with encrypted password. However, I couldn't find a way to change the password. If the drive is mount, the "Change Password" option is grey out. If the drive is unmount, the "Change Password" option is also grey out.

The only time when the "Change Password" option is not grey out and works is when I highlight an existing hard drive which is encrypted. However, I don't need to change my hard drive's encrypted password. I need to change the password of my encrypted dmg files.

In order to enable a dmg file to change password, do I need to create dmg file with some specific option(s)? I do not wish to create a new dmg file each time I need to change the password. I change the password often.

macOS Catalina 10.15.4

Thank you!