1. Check on
https://www.blockchain.com/en/btc/address/your_old_address if you have the expected Bitcoins. It should give you some peace of mind.
2. I hope that you downloaded and installed electrum from electrum.org (and not from clicking onto a popup) since there are some fakes too these days.
3. If you installed over the old version you should have the old wallet. If you restored from seed you may have had 1... address in the past and 3.. or bc1.. now => this is not what you want now, if you did this please tell. However, you have to tell more exactly what you did to get correct answers.
Edit: bitcoin transactions are irreversible, but if both wallets are yours, if you keep all the wallets you'll get your money right.
Make backup of all the wallet files. If you still have the old Electrum also try to backup.
File->Save copy.