install multi-media codecs & MS fonts:

sudo apt install ubuntu-restricted-extras

enable click to minimize on dock:

gsettings set 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:

browser.tabs.closeTabByDblclick true

fix volume level reduction caused by Firefox:

sudo nano /etc/pulse/daemon.conf

enable-remixing = no
flat-volumes = no