[Made a mistake with the options when importing - Can I easily revert or change options?]

Okay cool. Thanks very much. I'll try that. 

[Made a mistake with the options when importing - Can I easily revert or change options?]

Hi,
I am completely new to LaunchBox so please forgive me if I ask too many questions or ask for explanations.
It's probably best to treat me like a complete idiot. 😄

I have installed Launchbox, downloaded MAME 0.260 (merged) ROMS, and imported them.

I think I may have made an error when choosing the options and I chose "Use folder names instead of ROM file names for game titles." 
The reason I say I think I have made a mistake choosing that option is that a vast number of those rom files have no front cover or 3D box art ( I changed the settings to show 3D box art) on the GUI.
It appears that I can manually download the majority of covers but that is going to take an enormous amount of time.

Is the reason they are not showing because of the option I changed whilst importing or is it something else? 
If that is the cause, is there an easy way of rectifying it, or will I have to import them again, and will this cause issues with the existing import? 

 

The pictures showing above are ones I manually downloaded. 

Thanks for your help.