OK so I installed Ubuntu MATE again so I can play some games.
I love Papirus Dark icons. And I love the Advanced MATE menu.
When I had gnome icons I would change the advanced menu panel icon by editing the file located at
/usr/share/icons/gnome/22x22/start-here.svg or something along those lines.
Now what file do I replace to edit the icon that looks like that 9 square dots that Papirus uses as the default Advanced Menu Icon?
Thanks so much.
Aren’t the settings in the Mate Tweaks section which is pre-installed? I have not used Mate in a while so I won’t guess on any CLI input. 
Hi @starseed-pl,
Advanced MATE menu uses start-here icon from your theme. Perform a file search in your icon theme folder and replace target file(s).
Regards
Thanks. I found it. You can say it was a pale ale post. Forgot until my I checked my email.
The icon is located at :
/usr/share/icons/Papirus-Dark/[whatever-size]/panel/start-here.svg
Doh!!