How can I customize pre-order and back-order buttons on my website?

[ProfileMusic]

Hey,

We are after an app that can do both pre order & back order and we need to be able to change the title of these. 

Our website (https://store.profilemusic.net.au/) currently has a pre order section and we are using the PreOrder Me app to run this. When a product is out of stock, the button says "Pre Order" and customers are still able to buy it.  

We also have a back order (or re-stock) section, where we have products that were once in the store and had sold out, but we now have stock. If it's a back order, the button still says pre order.

Is there a way for the button to say "Pre Order" for the new stock that is incoming, and it automatically says "Back Order" for the stock that had sold out but we now have back in?

Any suggestions would be appreciated. 

Cheers