That's easy. I'd want to be Donald J. Trump for a day. I'd call the mother of all press conferences and spill the beans about what's going on in the USA. What's working, what's not. Who is taking from the country more than giving. I'd give up political correctness for truth bombs. I won't leave no stone unturned. All thats hidden will come to light. (Even Area 51).
I'd give my sources, I'll show what I learned about the behind the scenes machinations that make politics a vexation rather than a service , a bane rather than a boon. I'd turn Washington up on it's ear with plain truth, no BS.
The last thing I would do is ask everyone, help me fix our country. Every step of the way I'd open up the White House to suggestions., and assign a committee to work on them.
And before the day is done, I'd go sit with Melania and have a perfect slice of chocolate cake. I'd hug her and tell her I loved her, and go take a well deserved sleep.