Direct link on my Mega account:
Security is a Miui application, not in parameters, its icon is green.
Changing DPI will not change the size of the softkeys. It only causes the dynamic icons to disappear, like clock, agenda and weather.
---------- Post added at 05:15 PM ---------- Previous post was at 04:59 PM ----------
I was following your conversation too and this is the only file I could find. It was within /system/bin.
No, you have to mount the real data partition (check the fstab from TWRP to see the partition) to this folder, because you will experience a lot of issues if that's not solved.
If you could pull your fstab from MIUI install that would be great (can be in /system or /system/etc and named fstab.g3 or vold.g3 or anything, just search for fstab with your favorite file editor) and I'll check the mount point.
That being said, if the ROM works fine except for apps, I doubt that there is a problem with data partition because you settings couldn't be save if it was related.
I use fr-FR but why are you asking this ?