Select "always open this site in".
1) Visit the site.
2) Click the container button or use the shortcut.
3) Click 'Manage Containers'
4) Click 'New Container'
5) Name the container, click 'Ok'
6) Open the multi-account containers panel again.
7) Click 'Always Open This Site in...'
8) Select your new container.
But wait, you're still not done!
9) Open the site again in a new tab.
10) Check the 'Remember my decision for this site' box. (Didn't I already tell it to ALWAYS open the site in that container, in step 7?)
11) Click 'Open in [your container] Container'
That's how you create a new container to always open a site in with the Multi-Account Containers extension.
1) Visit the site.
2) Click the container button or use the shortcut.
3) Click 'Manage Containers'
4) Click 'New Container'
5) Name the container, click 'Ok'
6) Open the multi-account containers panel again.
7) Click 'Always Open This Site in...'
8) Select your new container.
But wait, you're still not done!
9) Open the site again in a new tab.
10) Check the 'Remember my decision for this site' box. (Didn't I already tell it to ALWAYS open the site in that container, in step 7?)
11) Click 'Open in [your container] Container'
That's how you create a new container to always open a site in with the Multi-Account Containers extension.