This bug report addresses exactly the same problem as bug 83364, but proposes and additional solution: Add a button that opens the Tools -> Outline Numbering windows as shown in attachment 105327 [details] to bug 83071. This button may serve as an additional hint that may take the user directly to the needed functionality.
Observed with LibreOffice version 188.8.131.52 and Windows 7.
Writing this bug report I found still another one that fell into this trap, see bug 74552.
Please don't report new bugs that report the exact same issue. Leave a comment on the original bug if you have a proposal for a different solution. Thanks!