Some constraints could be responsible for the shift. Some of them are dependent on the initial values of the edit bone so if that gets changed the constraint has to be reset. This is true for the stretch to constraint for example.
With that said, looking at that video, that looks very much like a rig that was generated by Rigify.
You really can’t edit those in the manner that you tried and more importantly you shouldn’t need to. One of the great powers of Rigify is that you can easily make changes by changing the meta-rig and regenerating the rig again.
Finding out that your pivot points are not in the perfect place is quite common and easy to solve in this manner.
It’s not impossible to edit the generated rig but it will require some advanced rigging knowledge and you will lose the ability to regenerate the rig with the meta-rig. I would strongly advise against it.
Watch this to have all your questions regarding Rigify answered: https://www.youtube.com/watch?v=-JSFcSxsaTs&list=PLdcL5aF8ZcJv68SSdwxip33M7snakl6Dx
It also seems your collarbone is out of place. It should start closer to the sternum and move towars the shoulder: