Please if someone can teach me how to do it then I shall be grateful.How to retain userHistory in docBlock of simulink without overwriting the old information?

 clear all;
 clc;
 bdclose all; 
 sys = 'test';
 load_system(sys);
 load_system('simulink');
 open_system(sys);
 k = get_param(gcb,'UserData');
 name = getenv('USERNAME');
 [Date, Time]= timeAndDate();
 new_info =char(name,Date,Time);
 k.content = cellstr(new_info);
 for i = 1:length(k.content)

     set_param(gcb,'UserData',k.content{i});
%      save_system('DocBlock')
%      set_param(gcb, 'UserDataPersistent', 'on');
 end

I am unable to save over all information. Like it is saving the last information and overwriting my old information