Group and individual tasks

Hi MarnaS777 - private / shared channels don't have a tab option for Planner as they're not connected to a Team (group) site. You could technically create a separate Planner for each user and use the 'website' tab option, but that will make it more difficult for you to have the whole picture.

If it's critical that tasks be hidden from others, I'd recommend using a List as you can individually security trim each list item to it's assignee.

Another route (and could add more accountability to the assignee) is to have each assignee create their own tasks and use this setting: How to enable Item Level Permissions in SharePoint | SharePoint Maven so they only see items they've created. You, as the List owner will be able to see all items.

I hope that helps!