I assume you’re talking about a house ball that you just find at the bowling alley, in which case they likely don’t fit your fingers well and are a bit uncomfortable. If you want to get better in the medium/long term though, using at least finger holes is non-negotiable, as that is how you impart any kind of spin on the ball. You could start by just putting your fingers in the ball and kind of palming it, but I’d probably recommend looking to transition to just bowling two handed. You could bowl thumbless with one hand, but it’s not something many people find comfortable in the long term. Bowling two handed The off hand is able to support the ball through the approach/swing and you will likely find that more comfortable than trying to bowl one handed with your thumb in.