Yahtzee wild dice

I know it's a bit belated, but I'll go ahead and answer this in the hopes that it can help folks in the future. For some reason, it says you need to buy coins because you do not have enough, but that is not true. Click on the gold die with the plus sign; this button is next to the cup on the left-hand side. Once inside this menu, click on the plus sign next to the die even though it has the message at the top. It should let you purchase however many you want, and then you will be able to use wild dice on future rolls at whatever point you need them. The number of wild dice you have will appear in a red circle next to the button if you don't immediately use them all. Hope this helps!