The interface language on the iPhone will automatically follow the "iPhone language" setting in the general settings menu of the iPhone:
Settings - General - Language and Region - iPhone language
Although the iPhone language may be in local language, I prefer to have the Jive App forced to the standard English language. This is because we have a corporate implementation of Jive and all browsers from our international locations are set to English interface language. Having Jive in local languages makes it very confusing for the users. "Streams", "Activity", "Places", "Groups", ... they suddenly are translated to meaningless local terms. And for the global IT department it becomes difficult to support the users.
Can the Mobile Jive interface language be forced to a certain setting, irrespective of the iPhone interface language?