They are both right.
You can hold a coin as long as you want without paying taxes.
when you sell one for another you have to pay taxes on your sell price - your buy price and that amount becomes your new buy price for the new coin.
you better either learn how it works or go to a tax expert. for stocks, brokerages keep track of this for you, but for trades in crypto, you need to know when you bought and how much you paid and when you sold and how much you paid. if you sell for $, you just pay tax on the price, but if you "exchange one coin for another" you need to know the exact price of both coins at the time you made the exchange.
Good luck and either do your research, or get help.
