Trump himself understands little of everything he does. He cannot be bothered to read simple texts, but he prefers images. His attention span is very short. So he is somewhat like a toddler. But in the end of course he does sign decisions and orders, even though he might have not read them fully. Someone else writes those documents he signs.

This is exactly why he is so destructive, he is too stupid to understand complex system but arrogant enough to still make changes.