1. Log into the API Portal CMS (<portalhostname>/admin)
2. Sitebuilder > Pages
3. For the page.xml file at the bottom, hover over the Layer 7 icon all the way to the right, and click into 'Properties'
4. Under the 'Custom' tab, change SEOTitle to whatever you'd like
5. Scroll down to the bottom and select 'Apply Custom Detail Changes'
6. Refresh the CMS page
7. On the same page.xml line, a box with a green arrow should've appeared now, please click 'Publish'
After this, the tab should've changed to what you typed in step 4: