Matlab App designer part 4: startup function , interaction between buttons , global variable

This is another video about MATLAB app designer. I will explain how to make a startup function, how to disable a button, how to create interaction between buttons and how to define a global variable accessible by all functions in the app.
I made a stopwatch to demonstrate these. At first I wanted to describe in detail how i made the stopwatch and meanwhile explain the features which i wanted to explain, but then i realized with my speed (very slow) the video will be very long. So I decided to only explain the features and not actual code of the stopwatch (maybe i show it in another video).
These days life is very busy. Not much time available for learning new things. It's unfortunate. But i am positive, things will change in my favor. On 15th January Alessandro defended his thesis. If you happen to read these lines, once more congratulation Alessandro.
Finance:
N=4, subs=142
Available budget (N):
142-100-4*(4+1)=22
Storage limit:
2^ln(142)=31,03
Now I am under pressure to make new videos, the storage is getting full.

[@vaibhavdhar]

Thanx to explain the call back function. I want to use start and stop button to run and stop the programs you showed in starting of the video. Please let me know how do this. I have three functions which have for loops inside them and I want to call these functions inside another for loop.

[@berfinaltuntas8061]

How can I change the text on the button after I click on it? app."name of your button".Text="newName" works but I want to iterate between the button name and new name everytime I click on it.

[@trickypunk6734]

thanks sir