Funding fee - Futures

Hi,

I'm just looking to gain a better understanding of leverage as it seems crypto exchanges intentionally make convoluted and hard-to-understand tips to increase your chances of trading without knowledge and losing money.

Anyway,

The funding fee: Let's say it's 0.0024%, and the countdown ends in 5 hours. If I hold a $15 position at 125x leverage ($1875), will I pay that fee on the size of the position ($1875) or the margin used ($15)? Now let's supposed I close my position before the funding fee countdown has reached zero. Do I now pay no funding fee, or will I pay the funding fee based on the closed position's margin or size?

Thanks.