DPI (dots per inch) is the printer resolution property. This dimension is used in software that communicates directly with a printing device.
PPI (pixels per inch) is the screen display resolution property. This dimension is used in photo edition software that prepares the image to send to print through the printer driver software.
Therefore, enlarge the image to the resolution you wish using the percentage scale and save the file, or change the PPI resolution value and send the image to print.
If you have not purchased inPixio yet, you can do so here.