What I want to be able to do is create an App that allows me to display and manipulate the fields for a specific client. No problem with that.
My question is I want to be able to switch between clients so that I now see the data for only one client at a time. Then switch to Client 2, etc. Do I have to create multiple apps, one for each client? I suspect there are much smarter ways to do this but I am new to QB.
Multiple apps will make you crazy, so that is not a good direction. Way too much duplicate, triplicate quadruplicate, quintuplicate development work.
Multiple forms if there are wildly different data element will also make you crazy, as its difficult for the record to know which form it should be using.
So, I suggest make the data elements to be child records. There are easy ways to set Templates to bring in std lists of children to a Parent. You might have different kinds of Children for data elements which vary in format a lot from each other, and then the various different children data types would be in separate embedded mini reports directly on the client record.