New centOS desktop install creating problems

I have 2 big problems:

  1. after installing centos 6.7 on a partition of a hard disk by formatting it, grub no longer showed me my linux mint and ubuntu mate boot options(situated on other partitions of other hard disks)

  2. the other partitions are ok, but I cannot read/write/execute all the files on those partitins, only some of them! (example: I wanted to see some terminal commands used on another partition, in mint, but cannot even read the .bash_history file, the system told me I’m not the owner, so I tried to change ownership, permissions, sudo nautilus but nothing)

Please help!

You can have a try with this:

http://pkgs.org/download/grub-customizer

and see if it detects your Ubuntu and Mind partitions.

As for your second question, check if your other partitions are mounted in read-only. Try creating a file and see what message you will receive.