English is not my main language and I don't know much about Linux, even though I'm using Bodhi for 8 years, so it was a bit hard to explain my problem, but enigma9o7 go it. So thank you so much!
The line that saved me was the last part:
Code:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key 51F523511C7028C3