I mostly focused on getting the head-to-body ratio correct, but you may have a point in that they seem a bit too wide at the moment... Let me see...
Taking a close look at the proportions, what you're actually seeing is that the human female model I'm using has far narrower shoulders that one would expect by averages. The head could probably afford to be a little narrower, sure, but that that oughtn't be a deal-breaker and wouldn't actually fix the shoulder ratio difference (an idealised proportion says that the total shoulder width should be approximately 2 heads(horizontal, at the collar bones), and on the human female model right now, it's only about 1.4. Narrowing the head won't change that (but it would make the visual affect seem closer to correct even though it doesn't).
The male human actually doesn't have this problem - all his ratios are within good averages. I just seem to have lapsed with the female and given her disproportionately narrow shoulders. (Though I do want to add as a side note that humans, and females in particular, often don't display this golden ratio anyway.... but for this case, I should be aiming for the standard, yes)
A slight narrowing of the head and a slightly broadening of the shoulders (and hips, by extension) ought to fix what your eye is seeing there, but again, these were just something I thought I'd toss up for a glance at the what I'm working with for later threads about posing and choreography - which only need a relativistic comparison. (Also, the tool I'm using is a bit finicky when it comes to making alterations in some specific areas of the model, and I sort of worked around that, becaue my skill level with this is minimal...)