You can change the seat numbers in an entire row by using the "Increases by:" field. This can be found in any section of your seating chart. This can also be seen when creating a new section.

This feature was used in a new section, labeled Balcony. The first seat number was 1, and each seat number increased by 2.

If the row already exists, click on the row letter. Click on Row Sequence. You can adjust the row starting number here.