https://documentation.libreoffice.org/assets/Uploads/Documentation/en/GS5.1/HTML/GS5114-CustomizingLibreOffice.html

To adapt shortcut keys to your needs, use the Customize dialog, as described below.

1)Select Tools > Customize > Keyboard. The Customize dialog opens. 

2)To have the shortcut key assignment available in all components of LibreOffice select the LibreOffice button. 

3)Next select the required function from the Category and Function lists. 

4)Now select the desired shortcut keys in the Shortcut keys list and click the Modify button at the upper right. 

5)Click OK to accept the change. Now the chosen shortcut keys will execute the function chosen in step 3 above whenever they are pressed.