Current questions and answers regarding the map editor.

Is it clearer now? In the hero settings (which you open with the spacebar), you can't set a value higher than 999. You can indeed do it in ArmySlots, but I rarely use the menu on the left and didn't notice it.

Why do you need a screenshot? I already know that you can't set a value higher than 999 there. That's why I didn't mean it that way initially and hinted at the tree-like properties. I've solved your problem.
Now you'll use the menu on the left ;)

If anyone still doesn't understand what bothers me: in the game, you can see the edge of the map and it just disappears into nothing =(. How can I fix this?

If the map is yours:
Have you tried changing the lighting? Try setting a different one.

By the way, regarding the green grass. You can slightly adjust it a couple of times with the terrain you want at the border, so that the green strip is in the middle - that way, at least the strip will blend a little with the surface.