Hopefully I understand your question correctly. When you set up one of your mail accounts in Thunderbird, the username needs to be set to the username used to connect to your account. There is a separate place to set your display name that will appear in the From field when others receive your messages. To do that: Go into Account Settings, for example: * tap the Alt key or the F10 key to activate the top menu bar * Tools > Account Settings In the left column, click the account you want to modify. (For example, where it says johndoe@gmail''.''com.) On the right side, find the "Your Name" box and edit to your actual name. Then click the OK button at the bottom to update your settings and give it a test. Was that what you needed?