Show a grid for a user to select a value and then use that value to filter the data shown in all forms


I know this might be a bit of a handful but tbh I’m out of ideas.

So I need the user to select one of “n” offices he has access to, and after selecting that office… all the data should be filter by that selected value in all other applications. For this I have 3 problems.

1.- How do I redirect the user to a page to choose one office.
2.- How do I use the list view for the user to select that initial value and store it like a “global variable”
3.- How do I filter the data shown for all applications

Any help or guidance you can provide is more than welcome.

Thank you all so much in advanced