You mean you want combine the Outlook Inbox of different accounts into a single file?
Yes, that's what I'm doing on my other computers.
It applies to Outlook 2007 and higher, including 2016 on Windows 10.
I do not see a Change Folder button as shown in the document.
Please bear with me for a while to check the details on different versions.
See the "Open File Location..." button on tool bar for this "Data Files" tab? That's it.
The outlook file is shown as an OST file (not PST). Will this procedure work for this type of file?
No. You need to manually create a PST file for combined accounts. OST file is basically a cache file and can be only associated with one account.
For more info, please check this MS official article.
This article does not tell me how to manually create a pst file, or how to rename and move the file.
I said in my initial question the outlook file is OST.
We're going in circles. I will contact Microsoft support.
Manually creating a PST file is very easy simple, see below the screenshot.
PST data file created?
Yes, and it made no difference. Then I tried to assign the pst file as the new outlook data file and my emails disappeared. After restarting Outlook it reverted back to the previous ost file.
Your responses are not specific enough for a non-expert to be successful, and may lead to making things worse. I will fix this with Microsoft tomorrow.