If You are buying on several eBay platforms,own several currencies on Your PayPal account and pay in currency You do not have on Your PayPal, always look which currency balance PayPal is going to convert and charge from! It may be important for Your economy on conversions.
I noticed when I paid my purchase in EURO PayPal wishes to charge me from GBP balance, but not from USD which I would prefer, and this should always be regulated manually,each time I pay.