Invisible Sticky Vertices? Issue rigging/weight painting figure


I have just recently started learning 3D/Blender and am working on a character in hopes of using to test in Unity for a game project. Gong through some of the tutorials, I’ve hit a wall as there seems to be an Issue severing ties of certain vertices of the figure from some of the indicated body parts I have isolated with the weight painting. I am probably using the wrong terminology but I hope you grasp what I am trying to convey. I’ve also added some visuals to as supplements. If any of you would give me some tips, it would be much appreciated. I am willing to upload the model if it would help you get a better look at the issue.

Thank you in advance.