On the On-demand toolbar, there is a Style (a.k.a., "Style current selection") icon. Clicking there opens a dialog box with the following four tabs in this order:
Text
Size and positioning
Background
Box.
Through my own tests and reading, I've been unable to determine what the "Size and positioning" tab controls. It only contains two setting. Page 58 is the only place where I can find any relevant reference to this in the "IBM Cognos Analytics - Reporting Version 11.2 - User Guide" but the function isn't really described nor defined there.
By the way, the Text tab also has similarly named settings for size and vertical/horizontal text alignment.
Anyone know what that second tab controls or influences?