Signed up just to help you guys out. Fingers crossed what worked for me, works for you. I had the exact same problem as above. I could edit my camera settings, but could not save a static IP.
Solution:
Background:
Originally I downloaded version 45 of the CMS client, but was unable to log in. Some password issue with that version meant I couldn't enter the settings for any device I had. So I discovered version 47, and it's bugs such as the static IP issue.
Running 1.0.0.47 I was able to change the default password of my cameras, but couldn't set a static IP. I theorised that between the 2 versions, I could set my password using version 47 so version 45 would understand them and give access to set the IP.
Actual solution:
Use version 47 to change your cameras password (I followed Jackies advice and logged in using a registered account, though im not sure how relevant that is to the process - perhaps it is). I've set both admin and rtsp passwords to be the same. eg. 12345678
Install version 45 (link here:
https://support.yooseecamera.com/threads/328/ ) and log in.
Edit the camera you wish to change the IP of and save it.
If you want to change the admin password, head back to version 47 (the static IP setting will not be lost).
NOTE: Resetting your camera password might end up with insufficient permissions in the yoosee app. In this case I had to unbind the camera in the app, and manually "add online device" using the device number from the CMS client and the password I had set it to using version 47.