I think I'm not understanding something because this should be easy.
From the signal website (https://signal.org/download/#) the instructions for installing signal-desktop are :
curl -s https://updates.signal.org/desktop/apt/keys.asc | sudo apt-key add -
echo "deb [arch=amd64] https://updates.signal.org/desktop/apt xenial main" | sudo tee -a /etc/apt/sources.list.d/signal-xenial.list
sudo apt update && sudo apt install signal-desktop
I followed these steps but every time I do I get the error "E: Unable to locate package signal-desktop".
It looks like the file /etc/apt/sources.list.d/signal-xenial.list didn't change when I ran that second command so I added the line "deb [arch=amd64] https://updates.signal.org/desktop/apt xenial main" manually with nano but still got the same error.