I have this problem with Neon (5.16), in Krusader only as root (as user it all ok): I can't change at all breeze icons.
Icons on root are set as Humanity (or other type) but in (root) Krusader I get always breeze icons, even after replacing kdeglobals in root/.kde/share/config with the kdeglobals of user. Nothing to do: always that ugly icons.
I can change icon of a single folder, but this is not a solution.
Thank you for your help.

As a matter of fact it is an old Kubuntu bug with root: to fix this problem use this command "kdesu -c "KDE_SESSION_VERSION=5 KDE_FULL_SESSION=true dbus-launch krusader".