my iMac has OS Yosemite 10.10.5 Does this prevent the Gmail app working

Hi there!

While Gmail doesn't have a Mac app, you may experience problems with Mail using an older version of the Mac operating system.

However, you may be able to upgrade to a newer version of macOS. Using this Apple Support article as a guide, Get system information about your Mac, let us know what year your Mac is and the model.

Jack

Just to add to Jack-19s fine post...

Mac's Mail App is not as modern as iOS's Mail app, Many eMail providers now require a separate App Password different from your eMail password…

It may just need an App Password separate from the gMail password…

https://support.google.com/mail/answer/185833?hl=en-GB

Apple Mail won't sign in to Google account - Apple Community

Note from PrestoWebDesign…

https://discussions.apple.com/thread/253701684?answerId=257151754022#257151754022

Trying to add Gmail account to Apple Mail… - Apple Community

Many eMail providers now require a separate App Password different from your eMail password…

Cannot do as it’s a 2011 27 inch iMac and 13 inch 2011 MacBook Pro using High Sierra as far as it can go cannot afford to upgrade to another. I just upgraded these with SSDs

so how to change the password in Mac ? Does that mean you’re asking me to change the password and the actual email in Google awesome password in mail in the OSx High Sierra?

Good news my friend! :)

how is this so . mail is not an app right ? Im confused

Apple's Mail App isn't updated except with the OS version, same for Safari... Apple's built-in Apps get outdated.

how ? was your mail on an older mac or what did you do ?