Please leave the mixer knob set in the middle.
Open Windows Sound Control. Set your AudioBox as the default playback and recording device. Then make sure each Playback/Recording devices Properties > Advanced tab has the same exact sample rate set as what Studio One or your DAW is set to. Also, make sure Studio One > Options > Audio Devices, the release audio device in background is checked. Once this is set you should be able to watch vids and use Studio One at the same time.
If the issue remains, please create a ticket to technical support.
Here is a link to create a ticket: http://support.presonus.com/hc/en-us/requests/new