[Resolved]  Olymp Trade — extra commissions?

Hello! I really like the fact that when i trade forex instruments i don’t have spreads, but commission per trade only. But i’ve noticed that these commissions vary. If i daytrade currencies, they are pretty small. But i have indices positions rolled over night and it looks like some cost is being added. I couldn’t figure out what this charge is and why its being applied? Is it this because indices have different commissions or this happens because those are overnight positions? Thank you in advance for clarifying!