After generating a new Steemit Account password, I was still logged into DTube. Try logging out and back in and try again. If this does not help, have a in here:
https://steemit.com/dtube/@tftproject/dtube-error-while-submitting-to-the-blockchain-please-help
RE: Channel Update - Von Youtube, Steemit, Minecraft und Co. [German / Deutsch]