updating UVW PNG

no Dimension is not design to rendor 'on the fly' and to be blunt Mac systems just wont manage that sort of workload.

the work flow is to edit your design in Photoshop [whatever else you use for images] and then replace the texture... yes decal is default and yes its possible to make Dimension models remember their settings so you don't have to tell it every time but the dev team changed that back in V2 so I assume someone decided defaulting to Decal is better