While assigning domain to the cube, previous projects' fluid object is appearing

I was practicing blender fluid simulation, but when ever I am assigning domain to the box, an image of my previous practice project appears over the new domain box, and without even baking, it is responding to animation. Its getting hard to write in words so I am attaching a youtube link to show you the problem.

If you guys know what might be causing the issue, please respond.
Thank you in advance.