Increase the partition size of container volume

But 3 things

  1. why another container with the same configuration works fine? I mean when I add files to volume in a docker container, the exact mount point in the host got increased?
  2. why do I have the exact files as same as the container in my mounted host for the first container?

check the below:

but after I copy file in the above folder in container, the size of / increased

  1. what is the right solution that I have to do?