Formatting

To apply bold and other formatting effects to your comments select the text and press the right mouse button.
Select Format Comment from the shortcut menu
SS
If you want to remove the User Name from appearing you can remove it from (Tools > Options)(General tab, "User name").
Before you remove it completely be aware that this User Name is used in other places as well though.

You can format your comments so they look different from your colleagues.
Use the highlight tool on the Formatting toolbar to change the background colour of the comment.
Use the font tools to change the font attributes.