On Mac, selecting a specific webcam resolution is only available with a few free apps, such as CamTwist Studio. This applies to any USB camera, not only the JeVois smart camera. Mac OSX seems to just decide which resolution to use and gives you no control over it. To use your JeVois smart camera with a Mac and to ensure a specific video resolution, you could edit the videomappings.cfg of your smart camera and keep only one resolution in that file. OSX will then have no other choice but to use that one. If you are a programmer, success has been reported using OpenCV to grab frames from JeVois on Mac, see http://jevois.org/qa/index.php?qa=114
On Mac, there is no access to camera controls (exposure, contrast, etc). Some third-party apps are availeble for this, however. For example the "Webcam Settings" app available on the Apple app store.
On Windows, selecting camera resolution and exposure, etc settings has become difficult too, and only a few free apps like AMCap allow you to select camera resolution. You may want to explore third-party apps for that, or, like on Macs, configure your videomappings.cfg with only one available video resolution. If you are a programmer, success has been reported using OpenCV to grab frames from JeVois on Mac, see http://jevois.org/qa/index.php?qa=114 as this may work for Windows as well.
iOS support: Using an OTG cable connected to an iPad (iOs 9), the iPad reported that the devide is not supported, for any USB camera (not only the JeVois smart camera). It seems that iOS does not support USB cameras.
Android support: Using an OTG cable, the JeVois smart camera was detected by some third-party apps but we were not able to successfully stream from it. More investigations are necessary.

Because of these caveats, JeVois is best used with a Linux host computer.