I created three different Terrain Types in data editor (jungle, urban, desrert) and it was no problem adding them under Map Texture Sets
Here´s the problem. The terrain editor tool doesn´t let me add more textures to my map with the terrain editing tool. As soon as I change the current texture set large numbers (only number one) pop up on the terrain.
EDIT: Found it!
There is a texture set button I didn´t notice
Remember you can only use up to 16 unique textures in your map, but you can organise them as much as you want under different texture sets. (Although sometimes it kind of bugs and leaves traces between texture sets but meh)
What and where was the button you found @newone900? Also, how do you use more than 8 textures? I have two texture sets added through map properties > TextureSets, so I can see both in the "Texture set" drop down in the terrain texture palette, but some of the textures just won't paint on the map.
Edit: To use the second texture set you have to go to the texture sets icon (in the top right corner within terrain texture menu, different terrain squares stacked on top of each other) Paint an area to use the alternative texture set.