lol, 36 trillion debt is not from any of the credit card or line of credit (like home loan, car loan or personal loan) Otherwise it's one hack of a credit card debt the American racked up.
Half of the problem for the US debt issue is that US have a non-responsible fiscal policy. This is really not as bad as it sounded, it just mean they can't (or rather, won't) balace the book. While the other half is because USD unlike most currency in the world, is also used as Forex.
USD have 57 or 58% share in the currency basket, which mean if things really reflected that way, the world is holding 58% of their forex in USD. If you are using it as forex, you essentially taking those currency out of their circulation, because you are storing them in another country. It does not goes into people hand for example , buying pajamas in Walmart.
The issue here is, you can't really have country like China, Japan or Australia to hand back the USD to you, on the other hand, you can't really print more to offset the USD other countries is holding, the solution is basically to jack rack up debt and push the settlement period. So you can "reuse" those USD without printing new bill or issuing new Line of Credit.
I mean, have you ever wonder why if you pay money from a bank account to another, it needed 24 hours to clear if both aren't the same bank, even if they are in the same country? I mean if we go by today IT standard, a buy order issue for the other bank and the sell order from your bank should be able to issue and communicate within hours, if not minutes. So it should be clear immediately like you would bank at the teller. But why the wait? That's because the bank you are paying to is looking for currency to buy and the bank you were using is looking for currency to sell, and they can't do it immediately. And that's why you have a day gap between a transaction. And you know if you ever done TT or international transfer, that time is lengthen to 2 to 3 business day, that is the time both bank need to buy and sell the USD in order to make the transfer. It's a constant game of cups and lids.