I assume you are on A06 module because you mention armbian-config instead of raspbian-config.
For the A06 there is this gearbox script DevTerm A-06 core CPU frequency scaling - #3 by yong to change the cores.
Or this GUI I made Gearbox GUI program for the Devterm A06
To change the governor from the terminal you can do:
echo performance | sudo tee /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
To change the frequency:
Make sure the core is online state
echo 1 | sudo tee /sys/devices/system/cpu/cpu0/online
Then set the frequency
echo 1416 | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq