Since I could not find the (easy) solution on the forum, here the answer:
Add the following text to your Mobile App configuration in Sprintr:
<preference name="orientation" value="portrait"/>
This needs to be added at Custom Phongegap/Cordova configuration.
Check the plugin https://github.com/gbenvenuti/cordova-plugin-screen-orientation
this can help you probably
you have to modifify your phonegap package(config.xml and index.html) with this plugin before you build it.
let us know what your results are