I placed close/min/max and so on buttons in the window header to the left side but can't change it for gtk application. Pretty interrupting when some buttons are on the 'wrong' side. Running Plasma 5.14.0 on Solus.
This should work just fine for GTK apps without headerbars, but is unfixable due to architectural decisions made by the GTK developers for GTK apps that do have headerbars. Which apps are affected? Can you provide a screenshot?
Created attachment 115729 [details] Screenshot Screenshot of remmina, Solus Software-Center and Kate (to compare).
Right, just what I thought: the misbehaving windows use GTK3 headerbars. Unfortunately, such windows draw their own titlebars and titlebar buttons and do not respect your choices. This is per the GTK and GNOME developers' design and I'm afraid there is nothing we can do to fix it. What I personally do is use the gtk-nocsd package, which transforms these headerbar windows into normal-style windows with shadows and a KWin-drawn titlebar that respects your preferences.