You can change the name of a particular section in the „Section Settings” section at the very top of the right toolbar.
Detailed description:
Hover the cursor over the particular section, and the „Section Settings” button will appear in its upper right corner (next to the „Delete,” „Duplicate,” and „Copy” buttons)
Click the „Section Settings” button, and the „Section Settings” section will appear on the right toolbar
Find „Section Name” and set the name of a particular section