Hi, I have defined my board with 2 layers and have completed it, but want to add another layer for test purposes. If I try to add a track in one of the user layers other than front and back copper, the track defaults to the top layer - i.e. I cannot route it on the user layer I have selected.
Board Setup → Board Stackup, then two pages: Physical Stackup and Board Editor Layers. Adding Copper layers to the Physical Stackup should do it, but the Editor layers may have some effect, too.