mjhjmtu

I am using Debian Stretch (9.5) and

sudo lspci -nn | egrep -i "3d|display|vga"

returns:

00:02.0 VGA compatible controller [0300]: Intel Corporation HD Graphics 520 [8086:1916] (rev 07)
06:00.0 3D controller [0302]: NVIDIA Corporation GM108M [GeForce 940MX] [10de:134d] (rev ff)

That means I'm using Optimus (hybrid) graphics chipset. By following instructions given here, I have installed bumblebee-nvidia primus:

sudo dpkg --add-architecture i386 && sudo apt-get update && sudo apt-get install bumblebee-nvidia primus primus-libs:i386 libgl1-nvidia-glx:i386

During the installation, I got a screen saying I have Nouveau driver currently installed and after reboot it will be set to Nvidia.

After installation completed and restart, I have executed: sudo lshw -class video, and it has returned:

 *-display 
 description: VGA compatible controller
 product: HD Graphics 520
 vendor: Intel Corporation
 physical id: 2
 bus info: pci@0000:00:02.0
 version: 07
 width: 64 bits
 clock: 33MHz
 capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
 configuration: driver=i915 latency=0
 resources: irq:124 memory:f2000000-f2ffffff memory:d0000000-dfffffff ioport:e000(size=64) memory:c0000-dffff

Also running inxi -Gx I have got:

Graphics: Card-1: Intel HD Graphics 520 bus-ID: 00:02.0
 Card-2: NVIDIA GM108M [GeForce 940MX] bus-ID: 06:00.0
 Display Server: X.Org 1.19.2 driver: N/A Resolution: 1920x1080@60.01hz
 GLX Renderer: Mesa DRI Intel HD Graphics 520 (Skylake GT2)
 GLX Version: 3.0 Mesa 13.0.6 Direct Rendering: Yes

But when I opened NVDIIA X Server Settings from the application menu, it said:

You do not appear to be using NVIDIA X driver. Please edit your X
configuration file (just run nvidia-xconfig as root), and restart
the X server.

But here. it is written:

As of stretch, you don't need nvidia-xconfig anymore, and a xorg.conf
file is not needed either in most situations.

Am I missing something or I'm using Nvidia driver?