Downgrade IOS 12.1.1->12.1

Follow exactly these steps:
Make an unencrypted backup of your phone using Itunes
Then go to:
MAC: ~/Library/Application Support/MobileSync/Backup/
Windows: %appdata%\Apple Computer\MobileSync\Backup\
							/!\ Skip this if you only see 1 folder /!\
After that if you see multiple folders, Go to Itunes and Click 1 time on "serial number" (like this: http://prntscr.com/lteasp)
You will see "UDID" (http://prntscr.com/ltebqc)
Now go back to your folder and enter in the folder with the UDID of the device (http://prntscr.com/ltecen)

In the folder, open the "Info.plist" file using notepad

Now go to this site: https://ipsw.me and search the model of your device
(If you don't know if it is Global or GSM, go to this site: https://ipsw.me/device-finder)
After this, click on your device model and in "Signed IPSW" you will see 12.1 and 12.1.1 (http://prntscr.com/ltejcb)
Take the number after the IOS version for the 12.1.1 (http://prntscr.com/lteenv)
don't close the site*

Now go back to your "Info.plist"; press CTRL+F and type the number from ipsw.me (http://prntscr.com/lteg3v)
After this you will see something like this: <string>[the number you searched]</string>

Go back to ipsw.me and now take the number for the 12.1 (http://prntscr.com/ltegtl)

In the Info.plist, replace the number you searched by the number for the 12.1
(Example for the Iphone 6s, replace 16C50 by 16B92)

Now press ctrl+f again and search for "12.1.1" and replace it with "12.1" (http://prntscr.com/lteibp -> http://prntscr.com/lteik4)

After that save and close the notepad

Now go back to ipsw.me and download the "12.1" ISPW for your device (http://prntscr.com/ltejk0)

After you downloaded it, go back to Itunes, shift click on the "restore" button (http://prntscr.com/ltekky)
And select the IPSW you just downloaded
Wait for the installation.
Once the installation is complete, on Itunes click on "Restore save" (http://prntscr.com/lteku6)

And you downgraded :D