How do ex Presidents fly around?

How do ex Presidents e.g. Presidents Clinton, Obama etc., get around. Does the US Air Force fly them around or do they travel by commercial airlines or private jet?

Added (1). Thanks for the "sensible" answers. @Pilsner Man what is the significance of "buckwheat" or am I just thick. Not from US.

Can I change my clothes during flights?

I will be travelling from Moscow to Italy and the from Italy to Tunisia. I wanted to know if it is okay to change my winter clothes to summer clothes in Italy's airport or if it is against some rules!

What should I do in LAX for 9 hours at midnight?

So I will be flying in to LAX soon. It will be late midnight, what should I do? I'm a night person who usually sleeps in the daytime (weird I know). I don't want to be spending all of this time just sitting in the airport. Is there a way to leave my luggage somewhere safe and go out to explore? Is there anything open late at night in LA? And if i will be able to get outside, where do i go? What type of transportation do I take? Do you have any recommendations?
PS: I don't drink, gamble, or do any of that.

Added (1). Also TSA could be a problem, is there a way to beat the lines if I'm going outside then coming back in?

Give someone else your plane ticket?

Me and my family recently bought plane tickets to go to Florida. My dad unfortunately isn't able to go on the day that we fly out. We're flying Spirit Airlines. Is there any way that we can transfer the ticket to another one of my family members, like my sister perhaps? Please help, I would really hate for me to spend all that money on a ticket and have it go to waste.

What happens to airline workers when flights are cancelled?

I might start working for an airline soon and since it started snowing a few times again here in chicago i began wondering what happens to workers when a storm hits and flights are cancelled? Or when flights are cancelled in general?

Is aviation going backwards?

According to link qatar airways boom supersonic order shttps://www.flightglobal.com/news/articles/qatar-airways-interested-in-supersonic-potential-al-446049/ will any supersonic plane in the next few years change the way we travel will boom or nasa or lockheed martin take over the long haul market

Will booms planes change the way we travel or any supersonic transport