Why can't I modify my hosts file?

[AC Question]

I cannot modify my hosts file

I use root and I cannot modify it at all, I tried changing permissions but it is denied, what do I do?
I use Sony Xperia M2 and I want to edit a hostname but the file cannot be modifed I tried using Root Explorer and I tried using ES Explorer but it didn't work, I looked for backups for the hosts file but it isn't anywhere to be found, I do not know all that scripts and big words stuff so be easy on me