Hi @Adrien361 !
The ability to designate a specific dashboard as your account’s homepage is only available on Enterprise plans.
For anyone who is on an Enterprise Plan, the admin needs to go to the general tab > click account > account home page. From there they can designate which dashboard is the home page.
For all other plans, the logic behind the first board that appears on the account is based on the first board you created. If that board was deleted, then it will bring you to your inbox instead.
I hope this helps! Remember to mark as solved if this answers your question 
Cheers,
Jenna