Looking for assistance with an IF Statement in PowerApps

I am working on an app and I am having trouble determining where my issue is with the IF statement I am using. I have multiple fields with a 0 value, if the user changes that value to anything greater than 0, a new field will be visible for them to enter a new value.

What is the formula to use that will do (2) things. 

 (1) If default value field is changed, make visible a "new" field where they will enter a new value.

 (2) If the new field is opened, I now want to hide the 1st default value and only show the "new value entered in the new field

Whereas:

Default value field = DataCardKey183

New Field=DataCardKey184

The default value of DataCardKey183 = 0

New Field would be visible only if the user enters anything greater than 0 in the default value field. Then I would want the default field to go away in that case.