Upgrade my browser
How to upgrade my browser
macOS sierra
macintosh
iMac 21.5″, macOS 10.12
Question marked as
If you have kept your OS up to date, then the Safari browser is up to date as well. There have been no Safari updates for that OS for some time and none are likely coming.
You might consider installing a copy of Firefox or Brave and giving those browsers a try if you can get a version that will run on High Sierra.