Hi @AmandaHuffman81 ...
That might be a permission setting that your school's Canvas administrator(s) have disabled. You'd need to check with them in order to see if you have that ability or not which @JeffCampbell has described.
EDIT...I just-re-read your question, and you're asking about edit section names and not not nicknaming your overall course name. So, the below information wouldn't apply for sections. You'd want to check with your school's Canvas admin as I've described above.
However...have you considered using the Nickname feature of Canvas instead? This is done via the Canvas Dashboard where you can give each of your courses a "nickname" that only you can see. Your students do not see your "nickname". And, when you add a "nickname" to your course, it does not change the official course name that was brought over from your school's SIS (Student Information System). The "nickname" then appears in a handful of places within your course...including the breadcrumb trail at the top left of your screen...and even when you import content. Also, if you don't like the nickname you chose, you can remove it, and the original course title will re-appear. You can read more about how to give each of your courses a "nickname" by looking at this Guide:
How do I view my courses in the Card View Dashboar... - Instructure Community - 618765
Check out the section about 1/3 of the way down the screen called "Create Nickname".
I hope this will be of some help to you. Sing out if you have any questions about this.