User Options

link - support.microsoft.com/en-us/office/control-when-external-references-links-are-updated-21e995b5-bab1-4328-8ab3-dd357fe0e653
link - docs.microsoft.com/en-us/office/troubleshoot/excel/control-startup-message
link - exceltip.com/tips/cant-update-some-of-the-links-in-workbook-right-now-how-to-solve-it.html
link - stackoverflow.com/questions/14908372/how-to-suppress-update-links-warning

Excel should always display a message if the workbook contains links that are not valid or links that are broken.

Ask to update automatic links

Check your (Excel Options)(Advanced tab, General, Ask to update automatic links).
The default is ticked.
This option affects every workbook opened on the computer

When this is ticked, a message that lets you confirm before linked items are updated.
When this is not ticked, the links are automatically updated, and no alert is displayed.

Startup Prompt

Check your (Edit Links > Startup Prompt).
If the workbook contains links you can control what happens when this workbook is opened.
This option affects this particular workbook and will be consistent for all users of the workbook.
This option still affects the workbook if a macro has been used open the workbook.

Let users choose to display the alert or not - This is the default.
This option will use the "Ask to update automatic links" user option to decide if the message should be displayed.
If the user has this checkbox ticked then a message will be displayed.
If the user has this checkbox not ticked then the message will be removed and the links will be automatically updated.

Don't display the alert and don't update automatic links
This option will remove the message and will not update the links.
If you want to update the links you can choose Update Values from the Edit Links dialog box.
If you are sharing a workbook with other people who will not have access to the sources of the updated links, this allows you to remove the prompt for updating.

Don't display the alert and update links
This option will remove the message and update the links.

Trusted Location

There is slightly different behaviour depending on whether the workook is saved in a Trusted Folder.

Showing the Message Bar

Check your (Excel Options)(Trust Center, Trust Center Settings, Message Bar, Showing the Message Bar).
This option affects every workbook opened on the computer

Update links to other documents (not other Workbooks)

Check your (Excel Options)(Advanced tab, When calculating this workbook, Update links to other documents).
The default is ticked.
This option affects only this particular workbook.
This seems to be workbook specific, however when I uncheck this option, save the workbook, and reopen the workbook, the option is automatically re-checked
It is possible to link to pictures, Word data or data in other programs. The linking is done via OLE and DDE.

When this is ticked.
When this is not ticked,

Using VBA

Private Sub Workbook_Activate() 
   Application.AskToUpdateLinks = False 
End Sub

The popup message disappears, but security warning displays instead.

Edit Links Dialog

link - https://docs.microsoft.com/en-us/office/troubleshoot/excel/update-external-links
SS

OK, no action is required. The link is working and is current.
Unknown, click Check Status to update the status for all links in the list.
Not applicable, the link uses OLE or Dynamic Data Exchange (DDE). Excel cannot check the status of these types of links.
Error: Source not found, click Change Source, and then select the appropriate workbook for the link.
Error: Worksheet not found, click Change Source, and then select the appropriate worksheet in the appropriate file. The source may have been moved or renamed.
Warning: Values not updated, click Update Values. The link was not updated when the workbook was opened.
Warning: Source not recalculated, click Open Source, and then press F9 to calculate the workbook. The workbook may be set to manual calculation in the source file. To set the workbook to automatic calculation, click the Microsoft Office Button, and then click Excel Options. On the Formulas tab, click Automatic under Calculation options.
Error: Undefined or non-rectangular name, some names cannot be resolved until you open the source workbook. Click Open Source, switch back to the destination workbook, and then click Check Status. If this does not resolve the issue, make sure that the name is not missing or misspelled. Switch to the source workbook, click the Formulas tab, click Define Name, and then look for the name.
Warning: Open source to update values, click Open Source. The link cannot be updated until you open the source.
Source is open, the source is open. No action is required unless you receive worksheet errors.
Values updated from file name, no action is required. The values have been updated.
Error: Status indeterminate, Excel cannot determine the status of the link. The source may contain no worksheets. Alternatively, the source may be saved in an unsupported file format. Click Update Values.

link - https://support.microsoft.com/en-gb/help/925893/external-links-may-be-calculated-when-you-open-a-workbook-that-was-las