How to change your FiveM Server logo

Login to the Server Control Panel.
Upload your logo image at the root folder of your server (Using the File Manager or FTP)
Edit your server.cfg file (By default it's under Configuration Files unless you're using a custom framework install located in a different folder.)
Look for the setting of load_server_icon and type the filename of your server logo after it as shown in the below example.
e.g. load_server_icon myLogo.png

Then save your server.cfg file and restart the server. Done!