Just for clarity I don't have a 360. Why are the 360 live free downloads different from the one live downloads? I only have paypal on record because I use a debit card instead of a credit card. Plus after the whole sony ordeal I'm reluctant to give anyone my card number.
I know you can select the downloads once they start downloading and pause them but I can't find a auto download disable setting. The reason I ask is because I want to grab live games when they are available and install them at my leisure. Plus my isp has caps

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I have another question. I have the new controller with the 3.5mm headphone jack. I'm using regular stereo headphones. Is there a way to control the volume with the controller or do I need to use a separate physical volume control?
For the downloads: Go to Settings, then to "Power and startup," and there's an option for "Automatically download updates and purchases." Uncheck that box, and you should be good. Comcast has a "cap" of 250 GB, but it says on their site that they aren't enforcing it now, and they haven't been since we switched 2-3 years ago. We're usually over 750 GB in used data in a month, but with my cousin having left the house a month ago (he streamed a LOT of Netflix and such), I expect that number to go way down.
With the 360 purchases, I'm not 100% sure the issue. They didn't have the Microsoft Account money thing in-place when the 360 came out. There weren't Xbox money gift cards and such. I guess they've just never integrated that method of purchasing within the 360, or they just haven't tied the 360's gift card purchasing into the site, for whatever reason. I have a debit card on-file with them as well, so you can put that on there, no issue.
The audio stuff, so into Settings, under "Display & audio," and there are sound and chat mixers that they added. I believe I saw in a screenshot/video that they are going to have those settings put onto the dash and/or snappable at some point, after another update. It might be an option already, once you have the new controller and the headset plugged in, I'm not 100% sure.