If your WiFi SSID or password has special characters like a ' mark (for example, Chris's WiFi), you can enclose the SSID and password in double quote marks:
uart:~$ settings set wifi/ssid "my-wifi-ap-ssid"
uart:~$ settings set wifi/psk "my-super-secret-password"
# Reboot after setting new credentials
uart:~$ kernel reboot cold