I cannot say with certainty what causes this without testing the report definition first but here are some potential reasons.
1. The crosstab above the misaligned textboxes grows horizontally because of extra column groups (see Table and Crosstab Groups). 2. An item to the left of the misaligned textboxes is hidden (see Showing and Hiding Report Items). 3. A binding that changes the location of the misaligned textboxes is applied.
If the options above do not apply to your scenario, you can try to place the textboxes in a panel and anchor it to the right edge of the report.
Last but not least, if you need additional assistance, please share your report along with some dummy data and I will try to suggest something more concrete.