Assigning previous units

How do I open a previous unit for a student to complete work without assigning the unit to the whole class? I am concerned that it will block the current unit from the rest of the class.

You can have multiple units open and assigned to students without blocking students off. I usually assign a new unit and leave all past units as is (open and assigned).

I have the units visible and the lessons as well. When my students go to access prior Units/lessons, they get a message that they need the teacher to provide access. I have looked at the class settings, but nothing is avaible to update.
This is making the end of the year very difficult since I have to keep assigning different units for students to access prior work and then re-assign the current unit I want them to work in.
How do I remedy this?

Have you tried going to the unit page. For example go to Digital Information ('21-'22) - for unit 1. On the top left you will see a drop down menu with the list of your sections. Make sure the unit is assigned to each section.
The button next to the section should be green. You can do this for each unit. If this is not working, please write to