Hi
Fadi Alzebdeh •,
Welcome to Microsoft Q&A forum.
As I understand, you want to change backup time of Azure Database for PostgreSQL Flexible Server.
Azure manages backup windows, and you can't customize them. The first full snapshot backup is scheduled immediately after a server is created. Subsequent snapshot backups are incremental and occur once a day.
You can manually take a backup by using the PostgreSQL tool pg_dump. For examples, see Migrate your PostgreSQL database by using dump and restore.
If you want to back up Azure Database for PostgreSQL to Blob Storage, see Back up Azure Database for PostgreSQL to Blob Storage on our tech community blog.
Backups are triggered internally as part of the managed service and have no bearing on the maintenance window.
Let us know if your ask is different to what we understood or have some other query.
Thanks