Change the Pop-up Message

Hi, I’m using this Browser Update plugin on a clients website and I’m needing to change the message but can’t work out how to do it, the message I need it to say is…

“We’re sorry – The features and pages on our website might not look right on your current web browser. For the best experience, use a newer browser such as Google Chrome, Apple Safari or Mozilla Firefox. They’re free to download for PC and Mac and only take a few minutes to install.”

Can anyone help please? The coding i’ve tried doesn’t seem to work (or i’m missing something).

Thanks in advanced,
Volta