KWrite does not write to txt file

[Tomek]

You probably don’t have access to write to this partition – see:

Shared HDD (win e Manjaro) error read-only file system

NTFS is not a POSIX-compatible filesystem and does not store POSIX file ownership information or permissions. This means that the ownership and permissions must be emulated by the Linux kernel upon mounting the filesystem into the virtual filesystem layer. Given that the filesystem is mounted somewhere under the /run hierarchy ─ which only exists in memory while the system is up and running, because /run itself is mounted as a tmpfs ─ you are obviously relying on the automagic from the udisks2 …