novice-trader, as far as I know, at very high level of understanding, the spreads are not affected by volatility. When volatility is high, you pay more for long leg. At the same time, you get more money for short leg too. So effect is nullified to large extent, if strikes are not very wide. Effect of volatility is just marginal different between 1 or 2 neighboring strikes.
Same happens when volatility is low. You pay less for long leg, and you also collect less for short leg. You profitability is dependent on whether market makes a directional move and your strikes delta changes in your favour.
If you expect market to remain in low volatility, side way range, then credit spreads are better. Or look for short strangle (with an extra protective option leg depending on market mood at the time) type of strategy are useful.
hope this helps
happy trading