linuxhelp
It helps if you use the correct commands.
These commands should (generically always) enable a change:
db configuration setprop phpmyadminmulti access private
signal-event post-upgrade
signal-event reboot
If you look at the wiki here
http://wiki.contribs.org/Phpmyadminmultiit says:
To limit access to local network :
db configuration setprop phpmyadminmulti access private
signal-event console-save
Note that usually a console save will require a reboot afterwards.