After you have created an account, go to Settings → Cash book settings. There you will find the Paid from cash register (section 3 Payment methods) section. Here, you can create different categories to which you can link the paid receipts later.

Have you also linked your accounting software? Then, you have the choice to directly record the receipts paid with cash in expenses or to record them on a balance sheet account. It is always advisable to specify all cash payments per receipt when counting, so that you can easily find them later in your administration.