Note that you cannot generally edit values in the past even if those months are displayed.  When the version is created the admin user can choose to make last month available for editing. 

Where values are open to edit you can click in and then edit the value (get blue outline on current cell).  As soon as you move away from the cell the totals and charts will update with the change. The cell gets a gray corner tag to indicate it has a pop-up. The pop-up shows the original value.

We have used a K to indicate numbers that are displayed in thousands to make the screen less cluttered.  If you go in to edit you will see the whole value displayed so always type in the full number.  Example 121.4k is displayed but when editing will see 121,436.  You should always just type the number, and decimal point if relevant.