- On the iPhone, open the Phone Settings app.
- From the Settings list, scroll down and pick the Safari app.
- To open the Close Tab option, go to the Tabs menu and select it.
- Select Manually from the drop-down menu.
- That's all; auto-closing of inactive tabs will be disabled instantly. Only when you manually close the tabs using the X from the tabs menu will they be closed.
Read More: How can you close all open tabs on your Safari browser all at once?