Store data in other screen

I'm doing a botanical App has stored a number of plants where each one has different fields such as weight, height, temperature and relative humidity.

For example ListPicker I select a plant of interest:

Plant: Sunflower

This is me visualize the specific fields of this plant:

Weight: 110 g

Height: 75 Cm

Temperature: 25 ° C

Humidity: 90%

As I need to make new measurements then the previous values will be overwritten by new readings. But how do I use a button that says "new reading" then I open another screen so you do not have to reselect the plant of interest but when the screen is opened recover from automatic way the plant previously selected and there already you can record the new readings for later storage.

Any suggestions as might happen?

first do the tutorials http://appinventor.mit.edu/explore/ai2/tutorials.htmlto learn the basics of App Inventor, then try something and follow the

 Top 5 Tips: How to learn  App Inventor

also see here How to work with Lists by Saj

and 

The recommended method of switching screens in App Inventor