Suddenly only displays about 20 sent emails how do I access the rest?uddenly stopped displaying sent emails

Never had any problem with checking sent emails before dating back years, as I often have to do this. But suddenly EMClient only displays a few of the most recent ones and doesn’t seem to want to search ones going back further than a couple of months. I haven’t altered anything, can anyone suggest a way to get EM Client to search and display emails going back years, please?.