I'm attending a course and today PS is acting really weird.
First of all using the dripping brushes gave me problems this morning: the brush (which is supposed to cover everything) leaves behind empty spaces and loses shape. In the picture you can see how after doing ok it became like on the white drip.
Second thing, after using the black paint on a layer mask in order to hide something, that something doesn't disappear, but it's still visible and it shouldn't.
Thank you a lot for your help. I've fixed the "dissolve" and the "20%" but after I've used it for the layer mask (it worked), it immediately came back to "dissolve" and "20%" on its own. 😞 How is this possible? I haven't set those commands