I’ve just installed Fireworks CS6 on my Mac. In a previous version of Fireworks I was able to change the size of my canvas from the default od 6000 pixels. Since then I’ve upgraded to Yosemite and to CS6 but no longer seem to be able to find the Fireworks CS6 Preferences.txt file to make changes.
There was a question on this previously but the suggestion doesn’t seem to work?
I think the file you are looking for can be found here:
~/Library/Preferences/Adobe Fireworks CS6/en/Fireworks CS6 Preferences
Note Fireworks must be closed prior to editing it. Also note that 10000 appears to be the hard limit for MaxDocSizeInPixels.