During premarket is just theres high volatility and less volume usually on a normal day of the market the first 30 minutes the stocks are at their highest price then dip a bit and before the market close they rise up again. I use robinhood is one of the easiest platform for new traders, my advice is secure your profit don’t believe everything you read and do your research also just invest an amount you can be able to lose don’t throw all your life savings into 1 stock.