newbie often run into losses when investing in new projects. ,i once bought new coins but i can't resell them. i think i have been cheated 
What do you mean? You cannot resell because the value is too low now that you're at a huge loss? Or is it because it was delisted? Quote
what can you suggest to us and how to find out if the project is a scam?
Majority are either scams or just plain useless. Don't buy any of them if you're a newbie. Stick with BTC.Quote
Is it true that new Coins can give big profits as people say on youtube channel?
Ignore youtube channels since most of them are only good on a bullrun. They disappear or go silent on a bear market. You don't need them. Just understand that probably 80 to 90% of tokens pumps on a bull market.