How to set default custom page in OAC for all users

Summary:

Content (required):

1. How we can set custom dashboard page as home page for all the users in OAC ?

We are aware in my account we can set under preference but need something which can be done for all users in one go.

2) However, after setting custom page as start page under my account -> preferences its working as expected only on first fresh login, and after that if i click on home it is going to default OAC home Page. Please suggest on clicking home icon also we need it go to custom home page as set in preference