2security/#pc yahoo dont reconize help

Hello,
Everyone said get two step.security. what they didnt sa
was what haooens when ur busy. You changed your phone number and forgot to update it at yahoo. I went on yahoo.com ok I put ztheta I put the password in.in it is correct.yahoo .informs me the dont reconize this device.That ive never uses it b4.Then it asks me to put my old phone number in .I did. Put id changed it. Theres no line u can press to update ur new number eh. Well .I get the help add.Nothing can help me.because .even thought I kniw the password.because I cant update my number it seems id lost my account.please I know There are highly intellegent educated your people out there ,who will not have a priblem fixing this.Today kids .are smarter than we were in our day. PLEASE WILL SOMEONE OUT HERE .TELL ME WHAT TO DO.I dont want to lose this screen name.It was given to me by someine special.Alanna.You can contact me ar ***@*** excuse the grammer and misspelling.Thank you..smiles