Teacher 863211, Pijiang, can tax problem impact I-485?

My parents took some money personally to US, I set up a US stock account for them (in name of parents) to buy/sell US stocks by using these money (they are NON-US citizen, so they don't need to pay tax to US). Now I withdraw some money from their account for my personal use, I have question:

1. do I need to pay tax to US goverment? (very very sorry to ask this quesion here, this is just a by-product question, if don't like to answer, it is totally understandable, I will ask other people, sorry)

 

2. if there is a tax problem, and US goverment want me to repay the missing tax, if I repay it later, does this impact I-485 applicaiton?

thanks a lot