If your Permalink settings not change to Post Name it show 404 Error for other pages.
SEO purposes (optional)
It is also a good idea for SEO purposes to navigate to ‘Settings>Permalinks’ and set the ‘Common Settings’ to ‘Post name’.
Same Solutions For Below Questions
1) Running into “404 Page Not Found” error on some pages on your website?
2) How to Fix Broken Permalinks in Divi Theme Or WordPress ?
2) Resetting Permalinks Structure in Divi Theme Or WordPress.