How can I change the 'Maxmum upload file size' to allow for larger files in Product Downlo

I am trying to 'Create New Product' in MarketPress for a downloadable file. When I click on the 'Upload File' button, a window pops up for 'Add media files from your computer.' However, it lists the 'Maximum upload file size: 1MB.'

How can I increase this maximum upload file size to reflect the larger size of my files?