When using External Sharing to share your plan with a customer or someone outside of your company, you can hide any Tasks that you don't wish to share with them.
How to Mark a Task as Internal Only:
1. Select the task you wish to exclude from External Sharing.
2. Click Edit and then select Advanced Options.
3. Tick the box for Internal Only.
4. Click Save.
A padlock will display on the Task card indicating that it is now Internal Only. Tasks with the padlock are not shared with anyone viewing the Board through External Sharing.
Tip: When working with Task Templates, you can add the Internal Only field to your template source f, and relate values of TRUE or FALSE for each Task. TRUE means the task will be automatically marked as Internal Only and FALSE means it will be visible by default. You can still edit these preferences manually after the template is imported.