You can use the
/font -d command to set the same font for the same type of window. For example, if you typed
/font -d 12 Georgia in a channel window, it would set the Georgia font at size 12 for all channel windows. You could also do
/font -sd 12 Georgia where the "s" part will apply the font to the Status window too.
Use the same command in a query window for it to apply to all queries too. Also see
/help /font.
Happy chattin'
Regards,