Important:
For changing the data in Excel the 3 key fields are needed when re-importing the data to BC.
Solution 1:
That can be done from the Lines part in the Sales Order page. There is a button in the right corner above of the Lines part with Menu "Edit in Excel". When using that the Sales Lines of the Sales Order are opened in Excel. It works when the O365 user in Excel (in Windows) is the same as in BC. Then and only then there is the Publish button shown in the Excel Data Connector Window right of the Lines in Excel for updating th data from Excel back to BC. Click it. After that close Excel with or without out saving the document, doesnt matter, go back to BC and reload the Sales Order page to show the changes.

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I tested that stuff also using page 516 "Sales Lines". That did not work, the Publish button was not shown in the Excel Data Connector page. That means you have to do that Order by Order or use solution 2.
Solution 2:
Export the Sales Line data using Config. Packages (RapidStart).
Create new package, use table 37 Sales Line, filter by Document Type=Order, Type=Item. Do not add the connected tables.
Select fields to export: The key fields Document Type, Document No., Line No., then the field Location and some more fields to identify the lines in Excel eg. No., Description, aso.
Export the table data to Excel, change the data in Excel, re-import to Excel file to BC.
Thats maybe the fast solution.
Solution 3:
A simple Batch Job (Report) or Codeunit which does the needed changes.
Can be done by a developer.
Solution 4:
Ask your ERP Partner.
cheers
Dipl.Ing. Franz Kalchmair