It would help if you changed all your passwords. It isn't easy to delete what is stored online. However, changing your passwords will not affect your security. Get into the habit of completely deleting all traces of sessions when you finish working in the browser, clearing cookies before closing. And to save passwords, use password managers with an open source code (for example, KeePass, Bitwarden). Or just save them in a blanket encrypted document.
Thank you for the suggestions although those mistakes happened in the past. I have been practicing some of the above like clearing sessions and cookies sometimes for a while now but for the password, I decided to take it away completely from anything digital. I have learnt series of lessons as a result of password mismanagement.
I really don't know much about the open source that you recommend or how to use them. I will appreciate if you share more details on how to get it or make use of it.