New investor question

Hello all! I started my investing journey around 2 months ago and I’m having a hard time understanding some things around the trading universe. I just sold two positions that I had on the exchange that I use (xtb) and I don’t understand why my longest position (with the same amount of assets) had less gains then my newer position. What is the point in holding if I lose profit in the long run? I’m probably missing something important. Can someone help me? Thanks btw