Hi I have had a look into this and have found this [https://support.mozilla.org/en-US/kb/manage-my-default-search-engines-firefox-android article] that will help you change the default search engine in Firefox for Android Beta. In addition to this you may want to use the Firefox for Android Beta search widget. If you have saved Firefox for Android beta to the device memory (as opposed to moving it to any SD card you have installed), you should be able to find the Firefox widget in the app drawer on your device. I hope this helps, but if not, please come back here and we can look into a different solution for you.