how to withdraw qtum from myetherwallet to an exchange which supports only the new qtum-adresses?
You will have to use qtum.changelly.com to swap your Qtum ERC20 tokens to the Qtum Ignition Main Network
You will require a deposit address that you generate from a Qtum Ignition Main Network wallet, which can be found on our Github:
https://github.com/qtumproject/qtum/releases/tag/mainnet-ignition-v1.0.2Make sure you encrypt the wallet, and then make multiple backups. Do a test send to make sure everything is working properly, then proceed to swap the rest of your tokens on Changelly