Im tring to find out how do you change under "compose" an e-mail the "signature part"?

Which email account are you using? I am assuming you are using Yahoo! so this is how you do it: Click on Options, on the top right hand corner, then choose Signature And from there, you can update and save what you want.

to do that, after signing in to your account in yahoo! mail, go to "options" in the upper right-hand corner of the page. under the management category, scroll down to "signature". you can then create a personalized signature... if before you saved your signature you clicked the [check box] to "add signature to all outgoing messages" found just beneath the text box, then your signature would be automatically added to all your outgoing messages. but if before you saved your signature, you left the [check box] blank, then you would have the option to click the [check box] to "add signature" for each email you compose... hope this could be of help to you... ;p