Created attachment 113330 [details] the design option is not available step 1: open the libre office presentation step 2: select a slide layout for your presentation step 3: after selecting a particular layout it is not available to do any design changes step 4: the design option for the slide layout is not available in the menu bar.
What you want is menu View > Master > Slide Master Or from the sidebar > Master Pages -> right click on the desired Master page and choose Edit Master. Closing as WorksForMe. Feel free to reopen if you disagree. Best regards. JBF
Created attachment 113417 [details] themes In ms powerpoint the themes are available in the design option but in libre we dont have such options
Created attachment 113442 [details] Master Pages in Impress In Impress we call that master pages. Best regards. JBF