Disappearing current conditions image icon

I shut down WD and restarted and this time the current conditions icon is now showing ok. However I then went into Setup/Advanced/Misc settings/Main Window Customise - to turn on a show custom image . I selected a Forecast Icon jpg from the Webfiles folder and ticked this. The image comes up on the Main Window but it is another copy of the current conditions icon not the forecast icon. What am I doing wrong?

I must say I find this part of WD very confusing - especially the Summary Images and Icons accessed through Control Panel. Could I humbly suggest that this is an area in WD which needs overhauling so it is less confusing.