Change accrual to cash

I do not have edit beside Summary, cannot click edit beside summary.
How can I change accrual to cash. I am on desktop edition.

In order to choose between a cash accounting or accrual accounting scheme, you first have to make at least one invoice. Afterwards you may go to the summary screen and click set period. An option will appear for you to change the accounting scheme

If you have a Set Period button, that is the same thing. But your software is out of date and should be updated. Once updated, it should look like this:


If you have neither, you have some bigger problem.