about get data in google sheet by double click in specified raw

hello i have one GOOGLE SPREAD  excel sheet ...in that i i have a data in b coloum from B4 to B300.......IN B2 I HAVE THIS TIME CREATED DROP DOWN MENU......BUT I HAVE TO SELECT IT BY SCRROL FOR BOTTAM SELECTION...I WANT TO DO THAT IF I DOUBLE CLICK ON ANY RAW FROM B4 TO B300 ....I WANT THAT DATA IN B2 AUTOMETIC......PLEASE HELP BY HOW TO DONE THAT IN SIMPAL WAY BY HOW TO DO BECAUSE I AM NEW ....HOPE GET SOLOUTION VERY FAST...THANKS IN ADVANCE....I HAVE SHARED A SAMPAL LINK OF EXCEL TO UNDERSATND ..PLEASE HELP ME ...HOW TO DO IN MY ENTIRE SHEET........https://docs.google.com/spreadsheets/d/1zGeZ6GEo76mONYOb4ZnAw4HXsp5b7p93JcCswLcqci0/edit?usp=sharing