Mac OS 10.9.5; QGIS 2.8.4-Wien; offending data here
I want to calculate the centroid of a polygon in meters. However, I cannot get QGIS to display in UTM and I cannot transform/project the data to UTM. I followed instructions on a number of answers to similar questions (e.g. here, here and here) and still have the data displaying in lat/longs (in the coordinate box at the bottom of the main screen).
In Project Properties/CRS I have set the project properties to UTM GDA94 / MGA zone 55, checked 'Enable on the fly' CRS transformations. In Project Properties/General/Canvas units I have selected Meters.
I added the vector data and defined current projection under Vector/Data Management Tools. I projected the data to UTM GDA94 / MGA zone 55 and saved the layer in that CRS. When I did this, the extent of the layer was showing in lat/longs, not meters. I've also tried to do this in a couple of other projected coordinate systems (WGS 84 / UTM zone 55S and GDA94 / Geoscience Australia Lambert) and am having the same problem.