The PTZOptics cameras have multiple simultaneous outputs and setting the resolution can be different for each of them.
Streaming:
When pulling either of the streams from the camera [ rtsp://<camera IP address>/1 (HD) or rtsp://<camera IP address>/2 (SD) ] their Resolutions, Frames Rates, I Frame Interval and CBR /VBR can only be set via the web interface in the Video Section.
HDMI / CVBS / SDI:
The resolution for these outputs is set via the yellow dial on the back of the device, and the chart on the bottom of the camera will help correlate resolution to the DIAL indicators.
(Note that a change to the resolution will require a reboot of the camera)
USB:
The USB resolution can be set using a tool such as AMCAP and the free version is all that is required for tuning the USB settings. Once installed you select the camera under "Devices" and then select "Options" --> "Video Device" --> "Capture Format" to adjust the resolution and FPS the "Properties" section there can also be useful for tuning the image.