In the Drawing Explorer, go to the Styles section, right-click -> Define Styles
and enter a name for the new style (let's call it Fred).
Click the Change -> Text button, go to the Bullets tab, select the bullet style you want and the text position, click OK.
What you might not have is Styles enabled on the ribbon ...
goto File -> Options
then Customize Ribbon or Quick Access Toolbar
select All Commands
and move the two Styles items into your ribbon or toolbar.
Now you can select your shape and the new style to go with it,