Select the Alignment tab to position the values within a selected cell or data region. You can only format the horizontal alignment of individual text within a text box. If you would like to set padding values on the text box or how text is aligned vertically, use the corresponding text box properties. For more information, see Text Box Properties Dialog Box, Alignment (Report Builder and SSRS).
Specify a value or type an expression that evaluates to the position where the text is positioned horizontally within a selected cell or data region. Click the Expression (fx) button to edit the expression.