Hi @s5004675 ...
In reading through your question a couple times, it sounds like you are wanting to assign percentages to assignments within an assignment group that you have created. I searched the Community to try and find similar questions to yours, and I found the following:
Solved: how to assign different percentages to individual ... - Instructure Community (canvaslms.com...
In particular, the response from @SusanNiemeyer seems helpful:
In Canvas, you can have Assignment Groups, but not Assignment Subgroups. In order for your final grade to be weighted properly, I would suggest the following Assignment Groups:
Assignments - 65% (or however you have broken this down)
Final Exam Section 1 - 5%
Final Exam Section 2 - 15%
Final Exam Section 3 - 15%
In the future, if you want just one Assignment Group for your Final Exam, then you'll need to work on your point system. For example:
Final Exam Section 1 - 10 points
Final Exam Section 2 - 30 points
Final Exam Section 3 - 30 points
Does this example help you with the setup that you would like in your own course? Essentially, she suggests that you set up multiple assignment groups instead of just one assignment group.
Please keep us posted here in the Community...thanks!