Stroke width doesn't change immediately

[Dopamine1]

Whenever I change stroke to .25pt width and try to draw a line after that, it undoes my changes and draws the line with 1.0pt width . If I change this stroke again to .25pt, then only after that I will be able to draw with my selected width. But it works only until I deselect brush tool.
It really annoys me the whole week. Is there any ways to make the stroke more obedient?

In illustrations:
1.

2.

3.

[Bill Silbert]

Could you provide the version of Illustrator and the OS you're using?

[Dopamine1]

The version is 19.0.0, if I get it correctly. My OS is Windows 10 Redstone 4.

[Monika Gause · Accepted solution]

If you want to draw just lines of non-varying thickness, don't use the brush tool. Use the pencil tool.

Also: in the appearance panel uncheck "New Art has Basic Appearance"

[Ton Frederiks]

Monika Gause

If you want to draw just lines of non-varying thickness, don't use the brush tool. Use the pencil tool.

Also: in the appearance panel uncheck "New Art has Basic Appearance"

Your uncheck "New Art has Basic Appearance" will do the trick.

But there is a big advantage of drawing with the brush tool, you will get a real time preview of the size and color of your strokes and that is missing with the pencil tool.

[Dopamine1]

Thank you very much! It's fixed now