Setting Email, Calendar, Write and Sheet as default applications

Setting Email, Calendar, Write and Sheet as default applications

I am having difficulty in figuring out how to set Zoho mail as my default mail client.  I want Zoho email, calendar to replace G-mail and Google Calendar.  I also want Zoho Write, Sheet to be my default applications. I can't understand why this is so difficult as compared to setting Google or Office as the default.  


Tarek Wanas
iCloudHero
tarek.wanas@icloudhero.net