Why are certain options locked on the publish wizard?

You offer a "let us help you design your form to match your website"

I am unable to switch the settings to allow this... 

How is this done?

Such options are available for card forms only, if you need to use them then you will need to switch your form to the card forms layout, note that you may switch between both layouts as you want. 

To change the form layout, please go to the settings tab while working on the form builder, click on the form settings section and the show more button, scroll until the very bottom of the options and change the selection on the "Form Layout" option: 

I hope this helps.