Depends upon how you are creating the signature. If creating a signature html file to attach then you set all your formatting before saving as html file. This means you have be using HTML formatting and have the 'Formatting Bar' visible, so that you can click on 'Bold' icon. Exactly the same as writing an email and selecting a word to be in bold. In the Formatting Bar, there are three icons '''A''' ''A'' A (the last one is underlined), highlight the text you want bold then click on the Bold '''A '''icon. The text would be shown as bold. Cannot see 'Formatting Bar' ? In a new Write message View > Toolbars > Select : Formatting Bar If you are using the Account Settings signature text box then you would see an example of how to write bold. See image below - where it says 'Signature Text' there is a check box 'Use HTML' followed by eg: example of how to write '''bold'''. You encase the words as shown in example.