It's late, so I'll be short.
1. It is not possible for you to have changed the owner in the service records, yet they still show the same. So either you did not change them, or you have the wrong field assigned on the layout, or both.
2. The quantity goes in your join table between Service Type and Products. I'm not quite sure how that would later be used in the actual Service Line Items for a particular ServiceRecord. The above join table is NOT the Service Line Items.
On a Service Line Item, do you have sometimes just a Product, and other times one of the ServiceTypeProducts (what I'm calling the join table above), or always just a ServiceTypeProduct? Or is a line just a ServiceType, and you automatically get all its ServiceTypeProducts (at the quantity pre-entered)? Or an unholy combination of the 3. It's important to know, as it may require some work to handle, beyond the level we're at.
But that's the next step. First you have get the join table right.
You did not mention IDs. I hope you're using them, because at the level you want to build, join tables, etc., you need them; likely you do have them.
I think you need to be a bit more technical, explain how you are using them. I don't have a very exact vision of your structure, at least not exactly how you're using IDs in the links. Because both your problems are caused by some small misunderstanding of how the relationships are working.