Choose the ribbon command Data | group Edit | External references 
to update and manage the external references in a document.
The command opens a dialog box that lists all the files to which there are external references.
The buttons in this dialog box enable you to perform the following actions:
▪Update
| This option updates only those external cell references that refer to the file currently selected in the list. For more information, see "Notes on updating external cell references" below. |
▪Update all
| This option updates all external references in the entire document. |
Tip: Alternatively, you can trigger Update all via the ribbon command Formula | group Update | Update data | Update external references.
▪Open
| This option opens the external file currently selected in the list. |
▪Change
| This option lets you choose a different file for the external file currently selected in the list. All references to this file will then be adapted accordingly in your document. |
▪Previous
| This option jumps to the previous cell that contains a reference to the file selected in the list. |
▪Next
| This option jumps to the next cell that contains a reference to the file selected in the list. |
Click on the Close button to exit the dialog box.
Notes on updating external cell references
Important: The values returned by external cell references are not updated automatically each time the worksheet is recalculated.
External cell references are updated only in the following cases:
▪When you open a document, all external cell references it contains are updated automatically (once).
| You can disable this automatic update – see the options described below. |
▪You can then manually update the external references at any time:
| To do so, choose the ribbon command Data | group Edit | External references and use the Update or Update all button in the dialog box as described above. |
| Alternatively: Use the ribbon command Formula | group Update | Update data | Update external references, which does the same as the Update all button. |
Options for updating external cell references
For updating external cell references, the document properties offer the following options.
To change these options, choose the ribbon command File | group File management | Properties 
and switch to the Calculate tab.
In the section External references, you will find the following options:
▪Update data on opening
| Here, you can specify whether all external cell references in a document should be updated (once) when the document is opened: |
| Always: When the document is opened, update its external references automatically. |
| Never: When the document is opened, do not update its external references. |
| Ask user: When the document is opened, ask the user if external references should be updated. |
▪Save external data in document
| If this option is enabled, PlanMaker saves a copy of all values returned by external cell references in the document. If the file for an external reference is missing when the external reference is updated, the value last saved will still be displayed. |
| If you disable this option, an error value will be displayed instead if you update an external reference and the associated file cannot be accessed. |
Note: The above options are document properties rather than global settings. This means that you can set them individually for each document.