I am afraid it is not possible to update encrypted files with Boxcryptor 2.x
Boxcryptor personal unlimited
Win7 64 - works fine
Android Nexus 7- works fine
iPhone iOS - no upload nor update. only download
Nokia Win Phone 8.1. same like iOS
All works fine, easy to use, fast, app can be protected with 4 digit code. thats really nice.
But I miss to change files in iOS and WP 8.1
Probanly OS restrictions?
What about integrated Text viewer/editor?