Weight Painting is causing strange results

I have a stickman character I’ve been spending days trying to rig. I just recently learned how important inverse kinematics are, and found a very helpful youtube video explaining how to make a simple, yet very effective character rig. https://www.youtube.com/watch?v=cGvalWG8HBU

I’ve followed to the steps to the letter (the ones that work with my model) but whenever I go to parent my mesh to the armature using automatic weights, it says that it couldn’t create a solution for some of the bones. So, I tried just parenting it without automatic weights. When I went into weight painting mode, I selected a vertex group, and started painting. I selected the right forearm, (I titled it Forearm.R) and started painting away. The weird thing was, it wouldn’t just weightpaint, it would also move the vertices along with it. I painted the entire model, and found that it created a slanted version of it leaving the bones in place. I tried doing the head, and things of that nature, and they worked fine. Nothing odd happened. I discovered that vertex groups with .R or .L at the end caused weird things to happen. Vertex groups like the head, and so fourth, painted normally. I’m not sure how to fix this!

You can download my character model here:

https://mega.nz/file/a3ozFJiQ#wQxvWk47RljVpT5AA9ZQJgspPKrPTZPXCsYVBz4px0c

I’ve tried seeing if the cause of this was my IK offset, and that wasn’t the problem. I really would like to have this issue resolved soon. Thanks, in advance. :wink: