Always on availability group sql account

Hello all

I am running a SQL server 2016 always on availability group. To provide access to the databases, i created individual sql accounts for each replicated database. When i fail over all the databases to another node i can no longer access the database . When i check the sql account under logins, and then check user mappings , the sql account is not mapped to the database. In order to get access to the database i have to run the following sql query. After i run this query the sql account is mapped to the database again. How do i keep the sql account mapped to the database after a fail-over to another node?

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