install multi-media codecs & MS fonts:

sudo apt install ubuntu-restricted-extras

 
enable click to minimize on dock:

gsettings set org.gnome.shell.extensions.dash-to-dock click-action 'minimize'

 
move the close/restore/minimize buttons to the left:

gsettings set org.gnome.desktop.wm.preferences button-layout close,minimize,maximize:

 
faster shutdown:

sudo nano /etc/systemd/system.conf

change and uncomment DefaultTimeoutStopSec=5s value and save, then:

sudo systemctl daemon-reload

 
fix Windows-Ubuntu dualboot causes wrong time displayed:

timedatectl set-local-rtc 1

 
Firefox settings:
close tab with double click:

about:config
browser.tabs.closeTabByDblclick true

fix volume level reduction caused by Firefox:

sudo nano /etc/pulse/daemon.conf

enable-remixing = no
flat-volumes = no