With gives a value a name for the length of one formula. Calculate it once at the top, then use the name as often as you need below. When the formula ends, the name is gone, so nothing is left behind on the screen.
The modern Combo box lists options for people to pick from. It allows several choices and a search box by default, so for a short list where one answer is right, turn both off. Then read the answer from Selected.
A SharePoint Choice column already knows its options. Choices gives them to your app as a table with one column, Value. Use it as a combo box's Items, and the app lists exactly the options defined in SharePoint, with nothing typed twice.
When a new screen looks like one you already have, duplicate it instead of building it again. Duplicate screen copies the screen with all its controls and formulas, and adds _1 to every name. Then you rename the copy and change what's different, starting with anything other screens send to the original.
On the narrowest phones, 360 pixels wide, my Power Apps app had three layout problems: a title cut in half, a button running off the screen, and list rows where a button left almost no room for the text. Each fix uses the screen's size, so phones get a tighter layout and larger screens stay as they were.
Incompatible types for comparison. These types can't be compared: Number, Error. means one side of a comparison has already failed. In my case, a duplicated screen compared a number with a context variable that only the original screen receives. The fix is to give the new screen its own variable.
This part builds the screen where a manager decides: approve a response, or decline it with a comment the employee sees. Then it tests the whole loop with a real employee in her own browser. That test found a bug: the employee didn't see her manager's decision. The fix, a Refresh button on every screen, ends the part.
On a phone, a header with two text buttons leaves little room for the title. The modern Button has a Layout property, and ButtonLayout.IconOnly shows just the icon. Switch to it only when the screen is phone-sized, ScreenSize.Small, and keep the button's accessible label.
A Refresh button lets people reload a screen's data without leaving it. The neat way to build one: move the screen's loading formula into the button's OnSelect, start it with Refresh, and make the screen's OnVisible select the button. Opening the screen and selecting Refresh then run the same formula.
Refresh gets a fresh copy of a data source, so the app shows changes other people made while it was running. It has no result, and it only works in formulas that run on an action, such as OnSelect and OnVisible. If your screen keeps data in variables, run its queries again after Refresh.
