If you root your phone, you can install the Xposed framework and install the Gravity Box module. This can set a new picture for the lock screen.
[quote=“Kathi, post:1, topic:21654”] Shutter sound of the camera: any way to deactivate (not turning phone on silent)? 
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If you install a different Camera App, for instance Camera MX you can turn off the shutter sound.
In the settings (Einstellungen) there is the option to “mount” the SD card. After you do this, you should be able to write and change data on the SD card.
Depending on the camera app - in some you are able to change the directory. But I’ve read, that Android is not so keen on letting apps store their data on the SD card.
Altogehter, I recommend installing FP Open OS - with this it is much easier to root and own the entire phone. I recommend reading this thread.