Hey, thanks! :3



In the Modifiers tab in the Properties panel - for anything tied to an armature, such as their hair - you'll find an Armature Modifier. There are some little toggle buttons at the top of that modifier, some of which are off by default. ("Display modifier in edit mode") Turning these on will keep the hair in its "posed" state when you enter Edit Mode. Then some "Proportional Editing" - which pulls nearby verts along with selected verts - will let you manipulate the hair to reflect gravity / motion. Press 'O' key in edit mode to toggle proportional editing. A search with some of these keywords should quickly lead to more info.



Best,