I cannot paint textures on Terrain except the first one.

I cannot paint textures on terrain except the first one. Same for the type of brushes, i can only select the first one. Changes in the Brush Settings doesn’t apply. These problems happens to new and old projects. I have uninstall unity and install again but problems remmains. Anyone know what i can do?

add textures example 4 textures which you use and the first texture will spread whole terrain. now select the second texture it shows light blue if u select and automatically it gives brush to paint on terrain. you can paint easily.