Its been a long time since I’ve installed unity, so a few things have changed… I’ve got my head around most but I can not seem to be able to hold shit to lower my terrain?
Select your terrain, and go to the second tab (paint height). If you have an up to date version of unity, there should be a “height” box with a numerical value in it. You can add a value to that box, and click “flatten”, which will raise the terrain, allowing you to lower certain parts. Be warned however, this will flatten the terrain. There may be another way around the issue, but none that i know of.