When you are working with some buttons frequently, it's better you create custom toolbar for those frequent buttons. It's just like desktop shortcut for frequently used applications.
Create A New Toolbar
To do this, open menu View > Toolbars > Customize > open tab Toolbar > click New. Name your new toolbar.
To do this, in the same dialog, press Add button. A new dialog will appears, select a button from category entries > press Add. Select buttons you want. If it's enough, close the latest dialog, press OK on the Toolbars dialog. Your toolbar will appear immediately on LibreOffice toolbar place. Usually on top.
Access It Easily
If you want to show or hide it, just open menu View > Toolbars.