>hello how are you, I need your help, I am trying to make a multi-company system but based on different data, how can I do it from a screen with all the companies the selected application is executed and after leaving that application I will return to the screen of the companies and to be able to execute any of the companies with only to put user and password only once

If you use DBFs, keep each company in separate folder structures.

Personally I prefer to store all the data on a SQL Server, where each company has their own database with different credentials. I also store some tables in a common database, here I typically store static lookup tables, and the table to select company from.