You can use it to buy lives, buy boosters or buy anything which you need real money to use. Alternatively, you may just save those gold bars. You cannot buy them in the "gold bars" interface. You need to go those items' interface.
how to use your gold bards to buy boosters.... I like the way it wasat first simple mone was deducted from you bank and you continue playing the same game that you payed and bought extra credits for, this gold bars is a mess it adds up and , and just taking your money? that not fair... i have 16 gold bars and i put the mouse on the