All users, except for collaborators, can share custom fields with other users unless their access role restricts it.
You can share a custom field independently of who a space, folder, or project is shared with. Someone can have access to a space, folder, or project (and all tasks within them), but if a custom field isn’t shared with them, they won’t be able to see the field.
The default sharing setting for a custom field is Share with everyone, but you can change this at any time.
Start by creating a custom field or editing an existing custom field.
Click the Share with option at the bottom of the field properties pop-up.
Share the field with the users or user groups that should have access to it.
Click Create if you are creating a field or Save if you are editing an existing field.
The sharing setting is applied not only to the current folder, project, or space but also to all locations where this custom field is visible. If you revoke users’ sharing access to the field, they will stop seeing it everywhere in the workspace.
What it means to share a custom field depends on whether or not a user has access to the folder, project, or space where the field is visible.
Option 1: Share a field with data and as a template
Users who the folder, project, or space is shared with can:
See field data that has been entered for items in the folder, project, or space.
Add the custom field as a template (see below).
Option 2: Share the field as a template
If users don’t have access to the folder, project, or space where the field is added, the field is shared as a template. These users:
Can’t access the folders, projects, or spaces where the field was added. Custom field sharing settings do not change a space, folder, or project's share settings.
Don’t automatically see the custom field on associated subfolders or subprojects, but they can add the field by clicking the + icon on the right side of the table and then selecting it from the custom field drop-down. When they add the field, they will see any field data that has already been entered for tasks in the subfolder/subproject.
Can add a custom field with the same name and field properties as yours to their own folders, projects, or spaces. However, none of the cell data from your field is carried over to them.