how to stop adobe fireworks from opening everytime you view a png?

Right click on any .png file and select "Open with..." > "Choose new default program". Once the new box appears, select Microsoft Picture Viewer or some other small application that doesn't take long to load. At the bottom of the box, before hitting OK, select "Always use the selected program to open this kind of file".

This will change the default, so when you double click on the image file, it will open with a more reasonable program. However, if you DO want it to open with FW in the future, right click, "Open with" > Adobe Fireworks.

Hope this helps!

Fireworks Png

Change the program association by right clicking and select open with. Choose default.

Assuming you're using Windows, right click on the picture, open with, choose default program, then choose whatever you want it to open with. It will now open with that by default.