If you were the supreme ruler of the world, what would you do to change the relationship between Mexico and the United States?

If I was supreme ruler, to be honest, the relationship between the United States and Mexico wouldn't be my top priority. BUT, if it came down to making a decision on what I could do, there's a lot. I mean if i was supreme ruler I'm sure people would listen to me. I'd call for world peace. I'd make it so there were no borders and that all countries would be able to thrive with the same amount of resources. I'd make sure every government was friendly with the next. Borders, in general, wouldn't literally have to exist. I'd make it so we are all one world instead of multiple countries and territories. That way there wouldn't be fear and everyone would be at peace. If world peace doesn't count then maybe lessening the strictness of the border and coming up with a reasonable way of letting people cross easily over the border and knowing they wont harm us.