How can i have a rotating brushtip with mouse like mspaint has?

Windows 10 paint has a brush called “textmarker” whose tip is always perpendicular to the direction of movement.
how can i have the same effect in kritas textmarker?

Don’t know “textmarker” but from what you describe you could pick a brush you want to transform to have this dynamic, press F5 to enter brush editor, click a rotation checkbox (which means torsion will be changing during the stroke, and then click on drawing angle checkbox (so it depends on the angle you draw).

In the brush tip options you may need to change the angle offset.

yes, i have already found that optin but when i use it something weird happens. when i dont press the mousebutton the indicator of the cursor turns beautifully with my mousemovements. but as soon as i press the mousebutton to actually draw the line theere is some kind of “jitter” applied to the brush so that the brush wildly turns at some 45° angles while roughly following the mousemovements doing the stroke.

Maybe there is other input checked apart from drawing angle (it needs to be only drawing angle).

If it doesn’t work properly maybe it’s a deeper issue - screenshot of the lines and btush settings would be helpful.

This may be because on a small scale, the movement of your mouse is not a perfectly smooth line, especially when you do a held left-click and you have tension in your fingers and hand. I also find this and the jitter is reduced if I use Weighted brush smoothing in the Tool Options docker.
Can you try that to see if it improves the situation for you?

yes. this option reduces the jitter thx. this was a nice additional puzzzlepiece to solve the issue. other things i noticed that help were putting the “brush distance” option to “automatic” so that at the end of the line you draw you dont have 2 rectangles overlapping at an angle, but rather a nice straight line. also it helps to make the rectangle the marker brush uses thinner so that at tight curves you dont have pixelated edges pertruding out of the line, but not so thin that there are gaps between the rectangles the brush draws. i found the optimal width/hight ratio (in the brushtip settings) to be 0.35.

ok. now how do i safe a brush preset permanently? i pressed the safebutten, entered name and even a custom icon. i closed krita i opened krita and it was gone.

Assuming you pressed ‘Save New Brush Preset’ button, your modified brush preset should be listed in the Brush Presets docker and still be there after a restart.
Is the tag filter box at the top of the Brush Presets do

Ah, I see that you found the cause of the problem and explained it in another topic but I dont have a problem with a ‘:’ in the name using the Linux appimage.
Can you try the Windows installed version or portable .zip instead?