How do I update my Mac. I cannot use my chase account unless I update

I see, by your tagline, that your iMac is running macOS Catalina (10.15). Which exact iMac model is it? To find out, click on the Apple logo that is on the left-hand side of the macOS menu bar. Then click on "About This Mac." You should now see something like "Late 2015 iMac."

We would need this information to know if you can actually upgrade to a later version of macOS. To run anything newer than Catalina, you would need, at least, a Mid 2014 iMac.

Chase Bank is the only institution still using the outdated and privacy-intrusive "user agent" query as the means to determine if a browser can handle their website, which was never a good idea to begin with.

If you are motivated to do so direct their attention to this excerpt from Apple's Safari Developer Documentation (emphasis added):

Important

Use feature detection to enable or disable functionality instead of relying on the name or version of the browser in the User Agent string. Learn how to detect available features on MDN…

The passage regarding feature detection in that document uses even stronger language:

"... this is a terrible practice that should be discouraged at all costs."

Unfortunately, Chase's continued and inexcusable use of that terrible practice leaves you out in the cold until they realize the error of their ways and correct it.

The workaround for end users who are unable to update their Macs to a newer macOS version is to use a different browser.

Consider Brave:

https://brave.com/

Firefox is a distant second choice:

https://www.mozilla.org/en-US/firefox/new/

The bottom line is that there is nothing wrong with your Mac's version of Safari, but that bank is using an outdated and ill-conceived method of determining browser requirements.

You do not need to upgrade your Mac. What you need is a different web browser.

I suggest using Firefox instead of Safari. I have used Firefox for many years and have never had a problems with it. I also use it with Chase bank without any problems.

have you tried system preferences

i use sonoma so i screenshotted a screenshot

Thanks John! I learned something new today about Chase bank.

Also +1 on the Brave browser. Been using it for about a year now and recommend it as well.

Brave is good. Hope they don't become evil.