Twitter is making changes to its mobile apps, with new versions now available to download for the iPhone and Android devices. But the biggest change has been reserved for the iPad app, which the company has rebuilt from scratch.The iPad app is now more visual and self-contained, with expanded tweets now built into the tablet version of Twitter. A single touch will bring up your friend's photo in all its glory within your timeline, along with video content and web page summaries, which you can play or read with a second tap in fullscreen mode.You can now easily track your interactions with other people and for the first time on the iPad, see at a glance who has mentioned you, retweeted or favourited your Tweets. Also here is personalised content and people recommendations via the 'Discover' tab and one of the more contentious changes on Twitter, a larger new header photo for the service. That's definitely a love or hate thing and appears above your Tweets on iPad, mobile apps and the twitter.com site.Finally, the iPad app now has a photo stream, allowing you to swipe through past shared moments.Some of that overlaps onto updated apps for the iPhone and Android handsets. The most obvious one is that new header photo, which is shared between all official platforms of the service. Photos streams are also on the smaller screens, which you can browse as thumbnails or tap for full screen. Android phones also get a pinch-to-zoom option.All of those changes are now live if you want to update your device.