Every time i wanted to install phpmyadmin, i faced this problem. Tried everything but this problem haven't solved. Migrating my sites here.
See this image : Image (https://imgur.com/bWDtws5)
I tried following thsi article - https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-phpmyadmin-on-ubuntu-18-04 as described and it seems like it works as expected.