how to show Back/Forward buttons in Android Studio 3.0.1 IDE

Click on "View" option in android studio(in top bar) and then click on "Toolbar" option.

In my Android Studio 3.0.1 installation, the buttons you seek are already in the main toolbar (see where the red arrow points):

To configure the contents of the toolbars, right-click over an open area in the toolbar panel and choose "Customize Menus and Toolbars..." from the context menu:

That will bring up a dialog where you can see the contents of the main toolbar and manipulate those contents:

In Android Studio 3.3 Canary 13:

Open View and then click Toolbar if it is unchecked. You will now get your toolbar with back and forward navigate buttons.

Best of Luck!