PowerApps Transfer Data From One Screen To Another Screen.
In this case, your question is about transferring content from one screen to another. For example, suppose you want to transfer data from screen 1 to screen 3 or something like this.
That is not how PowerApps works to our understanding. You do not generally transfer things from one screen to another screen. Even the controls that are displayed on one screen, actually can be referenced from another screen from another control for instance.
So in your case, you should instead choose one of these two options for your scenario:
Set a Variable / Use a Variable, or
use a collection.
Let’s give example with Set a Variable / Use a Variable. Let’s suppose it is Text value (be sure to be consistent with the type).
On App Start and On Screen 1 OnVisible use this statement:
Elsewhere in Screen 1, set the real value
Set(MyArbitraryVariable001,"My Text Value")
In Screen 3, try to use the value, e.g. in a Label text
On a Label, Parameter Text, put this as the contents: MyArbitraryVariable001
There you go.
You can also use ClearCollect, Update, Patch, etc.
To our understanding, a PowerApps Collection is interpreted (or can be used as ) a type of "data source" – so a Collection can be used if you want to use data source or collection related functions instead and depending on your scenario.
Variables and Collection can be used across any of the screens to our understanding as well. This is because a Variable and Collection is scoped to whole app.