How to change applications icons of Kde-Plasma 5

[fernando.cesar]

I'm using

Kubuntu 16.04
KDE Plasma version 5.5.5

In my applications I have these enormous icons. Eg., from Dolphin:

https://i.stack.imgur.com/1spSI.png

Which I cannot change. I tried "System Settings"-> changing everything in "Appearance", except the theme that remains Breeze because I couldn't find any other. But these icons remain the same. Help?

Thanks!

[fernando.cesar]

For some reasons my apps were using GTK+ settings.
I had to unset environment variable "QT_QPA_PLATFORMTHEME".
Alternatively, I was able to change icons by changing GTK2 settings, in "System Settings" -> "Applications Style" -> "Gnome Applications Style".