Another My Ubuntu 14.04 Installation, Problem and Solutions

When I want to update my system,

I got this error on my terminal

Solution:
For

from “GPG error:The following signatures were invalid: KEYEXPIRED”, It’s safe to IGNORE the GPG error. From this How can I fix a 404 Error when using a PPA or updating my package lists?, I CAN LEARN ABOUT THE PPA, HOW TO HANDLE THE ERROR AND DELETE/REMOVE PPA.
For

from “GPG error: Release: The following signatures were invalid: BADSIG” and How can i rebuild my ubuntu package lists??, It said to backup my current ppa list then do clean update??? BUT I HAVEN’T DONE IT YET!!! BUSY WITH ANOTHER THING

PHP/Apache error??
I got this message when I’m trying to repair the software update (I got my linux package broken in order to make upwork time tracker software working)

I got this error

when trying to access another disk (sdb3).
Solution: Start to windows 10 then restart/shutdown it. It took a few minutes to completely restart/shutdown windows 10. If I didn’t patient enough, the above error would be displayed again when I use ubuntu and try to access another partition. If I dont want to do the above (restart to windows again), I can use a trick from this http://askubuntu.com/questions/462381/cant-mount-ntfs-drive-the-disk-contains-an-unclean-file-system. but i never try it!

Installation of Cinnamon 2.8 Linux Desktop Environment (DE)
I need to install this DE because I see my screen pixel has black horizontal line and it’s growing everyday. I suspected it’s caused by the bottom panel bar of my Gnome classic DE can’t be hidden (auto hide) so the panel always appear and the black  line precisely at the border between the panel and the rest of screen.–> I DECIDED TO NOT INSTALL THIS DE RIGHT NOW, MAY BE SOMEDAY LATER. I FOUND A WAY TO AUTO HIDE THE BOTTOM (AND THE TOP) PANEL OF GNOME BY SELECTING ‘GNOME FLASHBACK (METACITY)’ INSTEAD OF ‘GNOME FLASHBACK (COMPIZ)’ I OFTEN TO USE WHEN I LOG IN MY UBUNTU MACHINE. BASED ON THIS LINK auto-hide bottom panel using classic gnome ?, I CAN USE ‘Alt + right click or Super Key + Alt + right click in an open panel area.’ THEN CLICK ‘Properties’ THEN CHECK ‘Autohide’. DONE!

When I update my system via ‘sudo apt-get update’ or via Software Updater, I got this error:

Solution: (ref: https://chrisjean.com/fix-apt-get-update-the-following-signatures-couldnt-be-verified-because-the-public-key-is-not-available/)
So add the key ’37BBEE3F7AD95B3F’ like this: