Yeah I just checked and apparently it doesn't automatically set to that, so that's my fault. How long does Electrum's (not sure if it's different than a standard transaction) take to stop broadcasting if it's never been confirmed take to cancel though?
I'm not sure if there is a set time for it to fall off. I'd recommend trying the accelerator linked above to see if it can help speed your transaction up.
Alternatively, you may be able to restore your seed into a new wallet and attempt to doublespend the funds with a higher fee.