Movable bubbles are different than attached bubbles, in that you can change their location to anywhere within your scene.
To move a bubble, tap and hold the bubble until it detaches from its current location. You’ll see a progress bar while holding the bubble, and when its in move mode it will lift up and its anchor will start rotating, indicating that it is ready to be moved.
Simply hold and drag the bubble to the desired location to move it.
Once you’re done, tap anywhere in your scene to deselect the bubble and it will automatically anchor to wherever you placed it.
If you change your mind at any point, you can repeat this process to move the bubble to a new location.