I want to revert to 1Password 5

Welcome to the forum, @feltonjohn, and congratulations on the shiny new Mac!

...when I installed 1Password, I accidentally accepted version 6.

The reason you were offered 1Password 6 for Mac is because it's the current version of 1Password -- and in fact, we're actually already beta-testing 1Password 7 for Mac. It's more than trivial to even locate a copy of 1Password 5 for Mac today, given how long it's been out of production. The last update to 1Password 5 for Mac was version 5.4.3, in early January of 2016, more than two years ago, and quite a bit has happened since then.

I assume, if you bought a new Mac, it came with macOS 10.13.3 or 4 installed, the current version of Apple's operating system. For comparison, the last time 1Password 5 for Mac had an update, El Capitan was still going strong (10.11.3 was released just a few days after the final 1Password 5 for Mac update).

Version 5 works fine for me and I would like to revert.

In short, we strongly recommend you not try running versions that are years out of date. As a security-focused company, we really can't recommend anything else but that you keep your software and OS version up to date. A lot of what's included in incremental updates is security-focused, patching newly-discovered vulnerabilities, etc.

More than that, though, we think you'll quite like version 6 -- or even the beta of 1Password 7 for Mac, if you're feeling adventurous. Give it a try, and let us know what you think! :)

@feltonjohn - sorry for the trouble! Can you please open 1Password and visit Preferences > All Vaults and let me know what you see there? Is there only one vault, or more than one? Can you give me their names? Thanks.

@feltonjohn - ok, that explains the "duplicate" information. It's not actually duplicated in either vault, it's that you copied the information from one vault (Primary, the older, standalone vault) into Personal (your 1password.com vault), but you didn't then delete the older Primary vault.

However, this is easy enough to solve. If you're certain you haven't been making a lot of changes to either set of your data since you took this step, then all you need to do is open 1Password Preferences > Advanced (the gear icon over on the top right of the Preferences window), and UN-check the box marked "Allow creation of vaults outside 1Password accounts." This will remove the Primary vault, leaving you with only your 1password.com vault.

If you've been using 1Password on other devices, you'll want to switch them over to the new 1password.com account as well: for those, you don't have to move the data (since you've already done so on your Mac). Instead, just follow these instructions to start over, and when you re-launch 1Password, sign into your account. Then everything will be synced up automatically and you'll have the same data with you, wherever you are! :)