How to change environment variable path from $ HOME to another?

The intention is to load with you all "created or downloaded" files, and mount it again on any LiveCD distro, leaving it as the default directory.

Note that the key to this reasoning logic is to only save files created and come from the internet, without any worry about saving settings (hidden files).

I did this:

$ unset $HOME

$ HOME=/mnt/sda1

$ export HOME

$ echo $HOME

$ /mnt/sda1

  

However, I can not record or execute anything there, I get the following message - Read-only file system   I already tried to change the permission with the command - chmod 777 /mnt/sda1 but it was impossible.

I have with me that there is something correlated to the user name .

I'm trying to find the solution.