You are not entitled to curse or use street language on a technical forum. Do that on your social networks.
Please (only once…), edit and modify each of your posts that fail to be civil. It’s not your party area here.
On topic, when I was using KDE, there were two utilities for Breeze configuration. One is still in System Settings (Edit theme) . The other one had an option for Single/double click to activate. After all KDE updates, this may have been removed, but you could try search for breeze in App finder.
Another place you have this setting is in Kvantum Manager.
The above have some meaning, only if you are using the relevant theme and widget.
So, you should post what are your settings for Appearance/Style etc.
Does single/double click not work for every application, or toolkit, or only on a few, and which ones work and how?