change icon for task manager launcher, system tray and Lancelot categories - Plasma 4

Hi everyone

these days I’m having fun customizing my plasma desktop but I ran into some problems:

[ol]
[li]creating a launcher for telegram doesn’t give me the correct icon of the application. I tried to add into the icon theme folder (actually I don’t know if I made it correctly) but the issue still persists. The strange thing is that before I changed the icon theme and the desktop theme, the telegram launcher had the right icon. [/li][li]I would like to modify the icons in the system tray so they would fit to the global icon theme. Some icons are displayed as they should, some instead are the ones included with the default plasma theme. It’s curious but if I hover the mouse cursor upon all the icons in the system tray, the preview-baloon that shows up displays the right icon. [/li][li]I’m using the Lancelot launcher but I cannot modify the icons under the various categories (applications, system, etc…) and they are the default ones. [/li][/ol]

Here I post edited screenshots related to my problem




What should I do?