By default, all PDFs open in the standard PDF-viewing window with a toolbar, if the toolbar is hidden by accidental touch, you can use the pin tool to show it again. This article will tell you how to pin the toolbar.
Using Pin Tool
1. Click any icon in the main toolbar on the top;
2. Then the sub toolbar will appear, hit Pin Toolbar on the right side to show and pin the toolbar.
Relaunching PDF Reader Pro
As opening a PDF file with a fixed toolbar is a default setting in PDF Reader Pro, you can relaunch PDF Reader Pro to restore default settings. But make sure that you have saved your PDF file before relaunching.