I'm rigging a character following this:https://youtu.be/tzJ39ZOhfQ4 and all seems well until i try and move my characters hand (or any part really) and it doesn't move according to where the bones are weight painted. For instance, when I move the hand the hip moves with it. I'll include some images to illustrate this point. the only difference I made from the video is when he pairs with the weights and his figure moves, mine does not at all until i select under the main meshes parent type and switch it from "object" to "armature" this allows it to move but in the way I'm describing. Am I supposed to switch the parent to armature? and whether I am or not then why does my rig either not move (while parented as object) or move as depicted in my screenshots (while parented as armature)?
That happens when you have unwanted parts of your mesh assigned to the current bone OR any other bone that is influenced by it. That includes for example child bones and IK chains.
An easy way to check to which weights is a mesh area assigned, is to ⇧ Shift RMB a mesh area while in weight paint. It will show you a list of all the weight groups found where you clicked, and allow you to switch between them:
You can also got in Edit mode and see in the sidebar the list of assigned weights for the selected vertices:
Edit mode has the advantage of giving you the ability to completelly remove a selection of vertices from a vertex group (which is slightly different than removing weights: having no weights only means the weight is zero, but still part of the group)
Figured it out! I am setting up a rig of a child, because she is being exported for use in unreal engine i need to keep scales accurate. because of this my girl is smaller than the default metarig. when i scale the armature to her I APPLY the scale then generate rig. this was my problem. instead i DO NOT apply scale then it generates the rigify controls larger at its default size and i scale it after and still do not apply the scale. It seems strange because every tutorial about everything blender always say TO apply the scale, but that was the problem that was causing it to not work right.