How can I change rotating mode? I have got a problem with rotating. I want to rotate a camera and it is rotating around the world origin, when I want to rotate it 'normally'. 
Also when I want to scale an object it is moving from world origin... How can I change it?
I hope the question is understable.
Your pivot point is set to the 3D Cursor, to change that you either need to press . and select "Median Point" to set it back to blender's default pivot point. or you can find the same options on the top of your 3D viewport as shown below: