I could not use the Arduino IDE (from AUR) with its default config on Arch Linux.

Change access rights

Run the following commands as root:

gpasswd -a YOUR_USER uucp
gpasswd -a YOUR_USER lock
chgrp lock /var/lock
chmod g+w /var/lock 

Change serial port

Edit your .arduino/preferences.txt

serial.port=/dev/ttyACM0