How do I turn off pressure sensitivity?

I have the same problem, spent hours with chat gpt trying to solve it, tried EVERYTHING. no luck

Could you please post screenshots taken at View > 100% with the pertinent Panels (Toolbar, Layers, Brushes, Brush Settings, Options Bar, …) visible? 

There is no 'save settings' button.

Look at the Brushes Panel. 

What are the settings in the Options Bar? 

My steps: 
I created a new Brush Preset, and then in the Brush Settings in the Shape Dynamics window, I tried to turn off Pen Pressure for this brush. But as soon as I start drawing, it instantly reverses back by itself. If I uncheck Shape Dynamics, it also reverses back as soon as the pen touches the tablet. How do I stop it from reversing? There is no 'save settings' button.
I tried to create presets based on Hard round and Hard round pressure size brushes.