In Classic Outlook for Windows, you generally can’t make Yahoo Calendar the primary editable calendar. That’s because Outlook ties the default calendar to the default Outlook data file, and Yahoo accounts are typically added as IMAP mail accounts, not as full calendar‑capable data files.
What you can check:
- Open Calendar in Outlook and see whether your Yahoo account shows its own calendar folder.
- If it does, go to File > Info > Account Settings > Account Settings > Data Files, select that data file, choose Set as Default, then restart Outlook.
This only works if Outlook has a writable Yahoo calendar, which is uncommon. If no Yahoo calendar folder appears, Outlook is syncing mail only, not Yahoo Calendar.
In that situation, the practical options are:
- Use Yahoo Calendar on the web as your main calendar, or
- Add Yahoo Calendar as a subscribed calendar in Outlook for viewing only.
For reference: Set default calendar
Subscribed calendars (ICS/CalDAV) are typically view-only in Classic Outlook, which is why you can’t set them as the primary editable calendar.
If you’re open to switching versions, New Outlook for Windows is worth considering. New Outlook supports Yahoo accounts and allows you to set a Yahoo account as the primary account, including calendar usage
For reference: Add or manage a Yahoo! email account in Outlook
Please let me know if this proves useful to you, or if you would like further assistance.
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