It’s hard to know how you expect this to work without seeing the actual data from the spreadsheet. Also, you should really never put a variable block inside of a set app variable block. You’ve just told Thunkable to create a variable with an empty text string as the name because you set app variable definition to “” and then set a variable with that variable as the name… anyway, it gets confusing. My advice: don’t use the set app variable " " block unless you have a really good reason to. Just use the set app variable definition block from the top of the Variables drawer.
Also, what do the blocks on the next screen look like?