Trying to Rig Joints and Limbs !HELP!(Specific)

I rigged my model but the joints seem to stretch and thin out when I fully extend the limbs.
Here’s what it looks like from the weight tool point of view.

Here is what they look like extended.

I’ve been experimenting and trying to fix this for hours with no luck. Can anyone help?

Around post 7 it shows how to change weights of bones.
Other than that i have no experience with rigging.

I know how to change the weight of bones. Are you suggesting that the problem is with the weights?

Probably, I have never rigged before, but weights sound like the problem

You have to play around with the weights until it looks right. There’s no other way to do it.

Could be the weights and it oculd be the positioning of the bones too, right?