How to change the scratch disk location of ZBrush

to change the scratch disk location you need to edit the path in the file ZBrushScratchDiskPath.txt in the folder C:\Users\Public\Documents\ZBrushData for windows or Users/Shared/ZBrushData for OSX.

ZBrush document size as default

to keep the changed document size as the default you need to hit the button, "Document > Save As Startup Doc"

fixing the issue that ZBrush Goz opens new maya scene everytime.

If you have the issue that zbrush Goz opens a new maya scene everytime, you just need to follow the below solution.

 copy "userSetup.mel" from C:\Users\Public\Pixologic\GoZApps\Maya and paste to C:\Users\taegi\Documents\maya\2016.5\scripts.