when to long or short a currency futures contract

I know it might be very obvious to some, but for me it is total confusion! In which cases does an investor long or short a certain currency futures contract (e.g. in a case where a US company is expanding to Europe, or a US company receiving a payment in, say, Euros, or a US company making a payment in a foreign currency…). I’d like to understand the logic and the reasoning behind these different scenarios… I always have the tendency to think the opposite of what the investor should do (long vs. short)… and which currency to go long/short! help! Thanks a lot!