First, make sure that you have not enabled full-screen mode, which shows only the page you are currently viewing by the user. Move the mouse cursor to the top edge of the screen and wait a few seconds. The panel will fall, and you can select the desired command.
If you want to completely disable fullscreen mode, move the cursor to the top edge of the screen, and when the panel down, click the right mouse button. In the context menu, select "Exit full screen mode". You can also use function key F11.
In that case, if the display mode selected is normal, but you still can't see the panel instruments, move the mouse cursor to any visible part of the panel in the browser window and click the right mouse button. In the ensuing shortcut menu, you can select the panels that you need for the job.
Click on its title bar ("menu Bar", "navigation Toolbar", "bookmark", "add-on Bar") with the left mouse button to set the marker. Your chosen panel appears in the browser window.
In order to configure the toolbar at your own discretion – add the buttons you need and remove the excess, just click on the panel, right-click and select menu item "Configure". This will open a new dialog box.
Check it with the list of available instruments. To place the selected object on the panel of tools in the application window, hover over the item, press the left mouse button and while holding it down, drag the icon to the panel instruments.
Use the items "Interval", "Stretch the interval" and "Separator" to give the toolbar the way you like. To remove any item from the panel, just drag it down. When you are finished, click "Finish".