To protect my security, every time I log out (PC) or at most return to the browser, I delete the cookies, especially immediately before and after online banking, and other sites where you have a registered account for the pagamento.
The rest of the sites, I evaluate… and yet one-off we need to clean the cookies, both on the PC and on the smartphone, just to empty the memory, and who knows for what other interests of others and not of ours…. Empty as soon as possible possible or you remember, this is my suggestion.