Yes, your changes from SBM Composer will overwrite the current settings in the Application Administrator, so you have to make sure the same settings are made in the composer or you will have to reset the field attribute in the Application Administrator after the deployment of your process app. 

This question is actually more complicated than it seems at first. The answer depends on how you move your changes from Composer.

If you deploy from Composer to the environment, the changes you made in the Application Administrator will still be there and will not be removed/overridden.

If you log into the Repository and use the Promote feature to move changes from your test server to the production server (for example), then the Composer changes are copied to the production environment. But, also the overrides from the Application Administrator on the Test server will be copied over to Production too. Any overrides on the production server will be lost and replaced with those from the Test server. Again, this only happens when using promote from one environment to another.

Hope that helps.

Thank you so much!! :)