I've been using Photoshop for about a year for digital art and design for various projects. However, there is one problem with the colours.
Every time I paint using a dark colour on the canvas and then a light colour over it, it makes the light colour neon. To make things worse, if I paint directly on the background layer, the colours become lighter despite my opacity being 100% on the layers, the brushes, etc.
To stop this from happening, I've been creating new layers every colour but that makes it exceptionally difficult to blend. Is there something obvious I'm missing?