When creating a character, the base structure of the face is altered based on the settings of Complexion, Age and Gender. In my opinion, these structure changes are actually very exaggerated and ruin faces. Female characters in particular do not even look human at first, and you have to work to undo the horrible deformation before you can actually get to designing the face.

What I would like to know is if anyone knows how I could alter these morphs to make them more realistic and subtle.

There is one more tab to the right in the upper part of that window (can't remember what it's called) but it will take you into the area where you can change all aspects of the face.

Elora Q

I don't know if this will help, but take a look at Django's Unique Features. He altered the texures of the age slider.
The results add quite a bit of variety to vanilla NPC's as well as allow you to choose what particular deformation / tattoo you want on your PC.
Look at my avatar. She has an eye tat that was added by Django's mod.

Maybe what he did can help you figure out what to do.