Switch to Settings tab and set payment threshold. For example, if your balance is 0.79 ETH. Then you can try typing 0.79. It will require your rig's public ip address. For this purpose, you can retrive public ip by visiting
https://www.whatismyip.com/ from the rig's browser.
If 0.79 does not work, you can try 0.75. These are the numbers but you will get the idea.
Good luck.
i have no more GPU.. and seems ho i can change withdraw limit just if i have an active miner / worker.
i think is not a good idea...
any other change to withdraw without have an active miner?