How do I edit object styles without having to delete and re-buy?? (Mac)

Hello all,

I just bought the Sims 4 for my MacBook. I'm a little frustrated with the build/buy mode, as it seems I can't edit the styles of a purchased item without having to delete it and replace it. I know there's a function for people with number pad keyboards (pressing the + button to switch through object swatches) but this doesn't work with my Apple keyboard. I'm wondering if there's a way I can do it on my Mac?

This is a pretty annoying process. I'd like to know how something looks without deleting, re-buying, and trying to re-place the object.

Thanks!

Edit: I bought the Sims pretty much specifically to build and decorate houses (it's relaxing for me) but this specific issue is making the process a little frustrating. Please help!