Select Alignment on the Placeholder Properties dialog box to set the horizontal alignment of the placeholder.
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.
General Display the text as calculated by Reporting Services. For more information about how text alignment is calculated, see Formatting Text and Placeholders (Report Builder 3.0 and SSRS).
Left Display the text as aligned to the left.
Center Display the text as aligned in the center.
Right Display the text as aligned to the right.