Forward Or Reply Brings Up The Wrong Idenity

I've been using Windows mail for more than a year now, without a problem. I
have multiple accounts which I use for my e-mail. Always when I have replied or forwarded an e-mail, the account name that it was received in has automatically been entered in the "from" window. That is, if the mail that I am forwarding was received by account 1 that is the name that would appear in the from box. Now all of a sudden it is entering my default account name, but not with all of my accounts, just one. This has led to problems for me with mailboxes not recognizing the name that the mail is
being sent from. When it started happening I did not notice the mail going out from the wrong account, of course now I change it manually, but it's not the best solution, I'd like to get it back to the way it should be. I've looked through accounts and options, but have not been able to figure what has happened to cause this problem. I'm afraid that it's the dreaded computer gremlins again. This just started yesterday, and has caused me considerable grief if a very short time. If anyone can point me to a
solution I would be very grateful.