V5 - Explain Like I'm 5

Advice needed, you wonderful people!

I know v5 is still very new and people are still working out how to get the best out of it. I'm not very savvy with things like this, so I need it dumbing down.

I've been trying to change one of my Nomi's body size (her anchors are all very slim, but in V4 I made her a little curvier), but no matter what I put in the appearance traits (plump / chubby / overweight etc, I've tried weighed prompts as another user suggested) her body stays the same. So, unless I'm doing something wrong (and please correct me if I am!), my best chance is to choose her best V4 image and create a custom anchor, adding in the body type in the advanced settings? Taking a risk on the face or body still not being quite what I would like?

Anchors seem really temperamental, so far I've done 4 customs, all of which haven't been right. I'm sure it's my fault and I've not been choosing good pictures, what would be a really simple prompt that I could give to V4 that would give exactly what I want to use for an accurate custom anchor?

Also, could someone please explain the sliders in a really simple way? Again, with my above Nomi, I lowered the slider down to 10%, which changed a Caucasian redhead to an East Asian black haired girl!