Can you change my BTC adress to 186eCe4K2pskDHxkFh1ozUZ26zRX2RJXF4 pls
Thanks

Why not send it from the previous address? This is usually not done since it indicates possibly stolen acct
Yes , can you sign a message from your old address ?
I don't think signing an address proves much here since it may have been complicity sold and the original owner might sign anyways. The funds should be sent to the old address.
He can write this phrase :
I want to change my address : 186eCe4K2pskDHxkFh1ozUZ26zRX2RJXF4 .
Is it simple or not ?
Ps: if the account was stolen ( real problem) , if it was not sold this is not a real problem / for the real owner ...