I've searched thoroughly and still can't find the answer to this question. I finally figured out how to prefill a form in an iframe using splinter, but it only works in firefox on my computer, while not working in another browser, let alone a mobile device. I've tried importing webdriver from selenium, etc. Still, nothing.
So far, the webbrowser works both on the pc and my android device to easily pull up a website; unfortunately, I can't get it to prefill forms in iframes. 
Can anybody help???
Thank you!!!
You can provide it as the argument when you instantiate the splinter browser object.
How can I force splinter to use a default browser?