Hi Kenneth,
The reason that you are observing this behavior is because when you restart MATLAB, the path of the custom component is no longer on MATLAB path.
More info on MATLAB search path: https://www.mathworks.com/help/matlab/matlab_env/what-is-the-matlab-search-path.html
When you click on "Configure for apps" on the component, there is a also a dialog that allows you to click on the "Add to Path" button that adds this component to MATLAB path. Now, when you open your main program and try to load this component, MATLAB knows about this component since it's on its path. But when you close and open MATLAB again, I assume that the current folder you are in is the folder where the main program is written and not the folder where the custom component is present. Hence, MATLAB does not know about your custom component and you have to load it to MATLAB path to be able to load it in your main program.
The simplest fix is to have the main program and custom component in the same folder.
Even if you prefer to have the custom component in a different folder, you can use the "addpath" command in the MATLAB command window and specify the absolute path of the parent folder of the custom component as the argument to this function.
>> addpath('<Folder_path_of_custom_component>')
This adds the custom component to the MATLAB path and you will be abel to load it to your main program. You don't have to use the "Configure for apps" apps option in the custom component, since it it meant to do other things, not just adding the component to MATLAB path.
Documentation link for "addpath": https://www.mathworks.com/help/matlab/ref/addpath.html
Since you wouldn't want to do "addpath" every time you restart MATLAB, you can specify this "addpath" command in "startup.m" file. For more information on this, please refer to the following link:
I hope this helps!
