Adjust serial console baud rate?

Hi! I have a Rock3A but im struggleing with the serial console. I tried using this guide ( for windows, but it didnt work. I suspect that my serial-usb adapter doesnt support the baud rate as it isnt listed in the device configuration menu of the device manager. Even with the correct baud rate in putty the output looks like this:

Why is the default baud rate even at 1.5m? Thats extremely high for transmitting text. I would like to lower it to something reasonable like 115200, but where can I do this? I found this wiki article ( that uses the file /boot/uEnv.txt to do this, but when I go to that file the first line says “# uEnv.txt has been retired.” so this is not the correct file anymore. The file also says to adjust /etc/kernel/cmdline, but even after changing all of the 1500000 to 115200 in the file I get the same output as above. Has anyone managed to do this?