Can't delete contacts

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Hello,

I have had Ymail for quite a few years. Each year it gets worse. a couple of months ago, itremoved some emails from a larger list like I had all my family in one called "family". Now it sends the emails to only half of them as the other half have been inexplicabably deleted. I also try to email my son and press his name when it comes up but my sister's name and email address come up when sending an email to my son so I have to manually type in his email address. I look at my contacts list and can find no way to delete contacts.. I can add new contacts but still the wrong email addresses come up when sending emails. I used to be able to do it but not any more. I do a search to see if the method has changed. I follow the instructions but there are no popup boxes any more for Ymail contacts. How can I fix these problems? Thanks.

System Configuration: Windows / Firefox 69.0
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