i have tethering enabled on my phone, so i can tether using bluetooth, but when i connect my phone via USB tethering turns on. how can i turn off...

Thanks for your question.

If I may ask, are you connecting the USB to sync it with iTunes?

Thanks again,
Glenn

I see, thanks for that info.

iTunes will prefer to use a wired connection if its available rather than the wireless. There is no option on the settings that will keep the bluetooth tethering on when you when you connect the USB cable unless you know how to tweak its system configuration, which I just don't have any idea, but I'm sure that your iPhone must be jailbroken to be able for you to do it.

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Thanks again.
Glenn

I apologize for the confusion and thanks for clarification.

For networking technology, computers or most devices are set to use the wired connection as the default cause this will give more reliable connection unlike wireless which is prone to interference.

Good thing you mentioned that. Base on my research there is a way to disable USB tethering from your Macbook but I haven't tried this as I don't have an Apple computer. You can try the steps below:

1. Rename you iPhone connection to something that you can easily recognize (ex. iPhone USB).
2. Connect your iPhone through USB then enable the tethering, then you will see the red light turns to green which will help you to determine which one is the iPhone USB tethering connection.
3. Then once you know which one is the USB tethering, at the botton just beside the add/remove button, click on preferences then choose 'make service inactive'.

Hope this would help.

Cheers,
Glenn