To update all reference grid annotations on the current sheet, in the Grid Annotations group, click Update and select Sheet from the drop-down list. Modifications to the reference grid annotations are retained.

To regenerate all reference grid annotations on the current sheet, in the Grid Annotations group, click Regenerate and select Sheet from the drop-down list. The reference grid annotations are regenerated to match the 3D model. Modifications to reference grid annotations are overwritten.