Hi @marcus obrien,
I understand what you mean. And I have done relevant tests on my device. As for why the default cookies of "Bing.com" or "microsoft.com" cannot be deleted, this is actually a by design behavior. Because in my test, some cookies of "Bing.com" can be deleted, but some "default" cookies always exist. Based on the cookies of "YouTube.com" and "googlec.com" you had mentioned, they work normally in my test and can be deleted normally.
So,
1.First of all, please check whether you have added the relevant website at "Don't clear"(Privacy, search, and services> Clear browsing data on close).
2.Secondly, you can also add the relevant website at "Clear on exit" (Cookies and data stored
Cookies and site data) to observe whether it can be cleared normally.
3.Finally, you can try to delete all cookies manually (as marked in the figure below). Then observe whether the cookies of "YouTube.com" and "google.com" can be deleted normally.
4.If it is convenient, you can also try to disable the extension.
In addition, you can also consider using the "InPrivate window" mode of the browser, which will not generate any data.
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Best Regards,
Jinxin Wang