I have a computer but it is not secured. I have an idea, maybe I will have to import my wallet in the desktop electrum wallet, after signing I will uninstall the wallet.
Even better: instead of importing your existing wallet, create a new one on your desktop and use it only for signing. Write down the seed phrase, and write "used for staked address on Bitcointalk" on the paper.
Importing funded wallets always increases the risk.
Im writing this post now just to let all know that my old Bitcoin address " 39oMwW6C9afRMAX8J3iDdDg12CN5V54dmw " is not longer active.
My new Bitcoin address is now " bc1qt7a65enqm7rn66vj7v78wx5jr5f269tl99en9clt5wae9cfnc0msjskm22 " and its shown in my Profil now also.
To be thorough: can you sign a message from 39oMwW6C9afRMAX8J3iDdDg12CN5V54dmw, and post a link to where you first posted it? Also: using only one address (with 351 transactions) is terrible for privacy, and inconvenient to distinguish payments.