You can use this link for your cookies in Firefox to turn them off, remove them.
Having said that, it is usually a website and/or a program running on the pc if it is over and over that still exists.
Have you used hitman pro yet? I highly recommend the free and paid version.
You can find that here:
You can download and use the free version from there.
Now, lets discuss your antiviruses. Many people think more is better. It is not.
You should chose ONE antivirus. Your windows 10 has built in Windows Defender. You can use one like that, or
one such as Norton, Mcafee, Avast, etc and use one scanner such as hitmanpro, malwarebytes etc for deeper scanning.
You can even have all of them on the pc. But, do not enable them all. Stick to one major and one scanner.
If you do not, they 'fight' for dominance with websites and clash. This actually allows malware to slip in.
Go through your programs and remove anything you see that you do not need or want. Look at the second line
next to the name of the program too. It tells you where it is from.
For example, Microsoft Office will have Microsoft next to it for 'maker'.
If the second line is questionable, look it up.
Such as myway toolbar/search engine. It is malware and takes over your browser.
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