If you imported your address into Electrum, the default behaviour is to send the coins back to the origin address. They cannot implement change address since they aren't going to generate addresses without seeds for you. The reason for this is to minimise confusion.
Thanks. Switching to a new address after every transaction is not feasible because of the high transaction fees. Not to mention the transaction time.
The current problem with ECDSA is that it is susceptible to attacks by quantum computer due to Shor's algorithm. This means that quantum computers can potentially crack ECDSA in a reasonable amount of time. However, the current progress of quantum computing is not anywhere near to the point for which encryptions are vulnerable to them. Even so, it may take some time for each address to be cracked.
Frankly speaking, unless you own thousands of BTC, no one would bother to try your address. It isn't free to use nor is it cheap and there are other things to crack than your BTC address.
Thanks. I don't own thousands of BTC, lol. At the end of all my transactions (after a few months), I'll probably move my BTC to a new address then. Hopefully, the transaction costs will be equal or less than what it is now (but who really knows).