This is a Dell Nvidia laptop, if I connect the HDMI plug to the 2nd screen it is not detected. I checked in the bios to try to turn off secure boot, but it is already on off.
Some HDMI cables are One Direction Only. Have you tried flipping the cable around?
I thought all HDMI cables were bi-directional, I just learned something today.
Also, make sure the 2nd monitor is enabled in Display settings.
Also, double check that your monitor is seen and enabled, in Nvidia X Server Settings.
Welcome to the Forum!
Because You use a Nvidia Card: Is Your System run in Wayland or X11? You can check that in Settings>About. If it runs in Wayland, switch to X11/Xorg.
To do that, go to the Login Screen (not the Lock Screen). simple reboot for that. On the Login Screen click on Your Profile sotaht the Password Field appears. When it is appeared, You should see a Gear Icon in the bottom right Corner. Click on it and choose the Option ''Zorin Desktop on Xorg'' and then log in.
Another Thing: Did You tried another HDMI Cable or only the one that You use?
Yes I flipped the cable, but didn't work as well
What is your terminal output of
sudo lshw -C video
fernando@fernando-Alienware-m17-R4:~$ sudo lshw -C video
[sudo] password for fernando:
*-display
description: VGA compatible controller
product: GA104M [GeForce RTX 3070 Mobile / Max-Q]
vendor: NVIDIA Corporation
physical id: 0
bus info: pci@0000:01:00.0
logical name: /dev/fb0
version: a1
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress vga_controller cap_list fb
configuration: depth=32 latency=0 mode=1920x1080 resolution=1920,1080 visual=truecolor xres=1920 yres=1080
resources: iomemory:600-5ff iomemory:620-61f memory:97000000-97ffffff memory:6000000000-61ffffffff memory:6200000000-6201ffffff ioport:4000(size=128) memory:c0000-dffff
*-display
description: Display controller
product: CometLake-H GT2 [UHD Graphics]
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
version: 05
width: 64 bits
clock: 33MHz
capabilities: pciexpress msi pm bus_master cap_list
configuration: driver=i915 latency=0
resources: iomemory:620-61f iomemory:400-3ff irq:222 memory:6254000000-6254ffffff memory:4000000000-400fffffff ioport:5000(size=64)
fernando@fernando-Alienware-m17-R4:~$
It looks like only the integrated Intel graphics are being used. No driver is shown for the 3070 GPU.
Can you run the following:
sudo apt remove --purge '^nvidia-.*'
Then:
sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt update && sudo apt install nvidia-driver-575 nvidia-dkms-575
Reboot and test...
Yeah!!! It worked perfectly!!!!!! Thank you so much!!!!!! 
I wish to learn all the things you guys know!
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The best way to learn can be to teach. If you look at issues other members are having, then see if you can figure out a way to help them - learning will happen that will benefit you, too.
Thank you 
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