@Klindar -- is that one computer running Windows 7? 8? 10? 11?
On it, what E-mail program are you using to view your messages? Windows Mail? Microsoft Outlook? Thunderbird? Gmail? other?
Do those programs have a "reset all settings to their default" option?
Same result on 4 different browsers (using Firefox normally)
Does that imply that you are using Shaw WebMail within all 4 browsers? The "settings" for your account within Shaw WebMail are not specific to whatever web-browser you are using. Those settings apply for any web-browser that is accessing your E-mail ID.