To change the stud spacing in walls for your entire job follow these steps:
1). From iPanel RMB click anywhere on the layout. Select Power Edit.
2). When the dialog window appears click on walls to expand the selection items. Under studs check mark Spacing.
3). From the Selections window click in the Value field and choose Add New Value.
4). The prompt at the bottom of Power Edit now instructs you to Enter new value. Type in the desired spacing and click Enter. The spacing is now updated.