Choose 'Option Groups' if you wish to have a window appear after selecting a product.
(e.g. A rib eye steak would have some free options of rare, medium etc and maybe some charged options of chips, peppercorn sauce etc.)
To create a custom option group, first create it as a product.
This will ensure that it appears in the options window so that you can select it.
Select the options you wish to add to this product at this point and click 'Configure Option Groups'.
The item(s) that you have selected will be imported into this next window - 'Option Group Settings'
Here you can choose to charge for all items or only selected ones.
Maximum amount of options will automatically dismiss the option window once the maximum amount of options have been selected, ideal if certain food dishes come with a choice of side dishes.
On this screen you can force the selection of options and also set a limit, if any, on the number that can be chosen.
If, for example, these are for a 'Steak' then you would only choose one from the options of 'Rare', 'Medium', etc.
Click 'Save' to apply changes to the product.
Repeat the previous steps to add more levels of modifiers to your product, if desired.
Once you have added all the modifiers you want, simply click 'Save' and then 'Update' on the 'Option Groups settings' page.