What are the main items that have caused it?

It is unlikely that as a non-accountant you will have to prepare cash flow statements.
Your accountants will do that for you and present you with them from time to time.
Unlike the profit and loss account and the balance sheet, a cash flow statement should be accurate. There are no assumptions or estimates to make. It can be considered to be entirely an unbiased factual statement. You do not need, therefore, to ask questions about the way that it has been compiled. You can take it at its face value.
We will assume that after studying this chapter you know where the information comes from and what it means. So what should you do with it? What questions should you ask? We suggest that the following ones may be appropriate.