The tips here are for advanced usages of composer and its assumed you have read about using composer and have a knowledge of your vendor packages to be updated. Let's consider, you want to update only one specific yii2 vendor library, without updating all the other extension packages?
Ok, you have installed a Yii 2 basic or advanced app for the first time and completed the post install steps. You have picked up a few extensions to install for the first time as well. You would already see a composer.lock file in your application root folder.