We work remotely, my co-worker and I have uploaded the same file to YouTube with different results:
Initially I used the Color Picker to match his color but upon uploading it to YouTube and comparing it with his videos I realized the color was off. Next I used his source (A Keynote Presentation) changed the title and exported the png. Above were the result; two Macs running FCPX, same png file -two vastly different results. (Viewing in Chrome)
I will say I haven't yet compared our export settings but I've never had this issue with export settings before.