In ArcGIS Online Map Viewer, the print preview (Show print area) area extent changes after the DPI value is modified when the scale has been set.

Workaround

Using the keyboard shortcut (press Shift and drag a box on the map to draw a preview area) prevents changes to the DPI value from affecting the extent of the print preview area. The keyboard shortcut is noted as a tip in the documentation: https://doc.arcgis.com/en/arcgis-online/get-started/print-maps-mv.htm

Steps to Reproduce