Your wallet generates a new address each time the "old" one receives bitcoin. It is not a bug, but a feature that tries to protect you from unintentional address reuse. Addess reuse is when you use the same addrress on reccuring basis. This is not against the rules of Bitcoin protocol to reuse your address, but it kind of bad for your transactional privacy. So, after you receive a payment, you still have control over the address and you can reuse it freely. Don't be afraid of making transactions on bitcoin network, but do it wisely. If you are unsure if your payment will reach its destination, try to send a negligible amount and see if it succeeds.