Creating a 300dpi image in Dimension

I have been tasked with creating a series of images with specific size needs.

3000px X 3000px @ 300dpi

When I create the image at 3000px X 3000px is exports at 72dpi. How can I easily fix this? Hoping to just do it in Dimensions and not messing around with a lot of different images going back and forth from Dimensions and Photoshop. 

I used to do this all the time, but Dimensions has updated and now I can't. At this point I'm seriously considering installing the old version