The checkbox has gone.
Labels work differently now from version 19.
Set the label you want in the label tool and then just click on your window (plan or elevation).
You can now have multiple labels on an element.
Barry.
One of the forum moderators.
Versions 6.5 to 27
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11