Brush stroke turns swirl

[Ducati]

Hello

This seems like such a basic problem, I'm a bit embarrassed I can't work it out myself, but here I am.

I'm using Designer on a Mac desktop.

I'm trying to 'paint' a mountain scene and I want to not use pixel persona. I have drawn a basic mountain skyline using the pen tool. I want to add some highlights and shadows. I was going to select a brush with some texture and add strokes that made a sort of upside down V shape - or perhaps more a ✓shape. The problem is that all brushes add this loop when I try to make the turn. 

I've tried looking at the brush properties, and can see the corner options, but they don't actually seem to do anything.

I had to go into Krita to show you what I mean. They have a knife tool (like an oil painters palette knife) that works really well.  So this is what I am trying to achieve:

 

I can't find anything similar to the palette knife in AD, but with a and this is what I get in AD (the 3 images are with the corners set to fold - overlap - pull):

Can anyone please advise how I can stop this swirling? Occasionally the 'overlap option creates a flat top but it's such a strange shape it doesn't help with what I'm trying to acheive.

Many thanks!

[DWright]

Can you please confirm the brush type that you are using

[Ducati]

Hi

Honestly, I can't remember the specific brush I used in this example, but it doesn't matter so much, because I get this behaviour with 'all' of them. Just to be sure, I just tried - a brush from all the following categories: Ink, Watercolours, Oils, Pencil, Basic and (one I imported,) inkBrush Vector - Render. As far as I can tell, it doesn't matter the brush, or the corner setting, they all do this.