Blurry when reopens saved document

Hi,

When I finish drawing, I click on the house icon (top left hand corner) to save the document into fresco and come back to it later on. The message "saving document" pops up. When I re-open the documents, they are always a little bit blurry. However, if I chose to export them instead of saving them they re-open fine. I don't understand why. It is very frustrating because I need to be able to save them into fresco if I want to keep on editing them later on. I use live brushes and pixel brushes. Please help. Thank you. Sarah