Make sure that you read all of the following as there are three scenarios. Note the differing iTunes version numbers mentioned below. You will encounter only one of the three.
- If you downloaded iTunes directly from Apple, click on iTunes' top bar menu Help/Check for Updates. If there is an update available, follow the prompt to download it and iTunes will do the rest of the work. If there is no update available, a message will state that your version (12.12.7.1) is current (see the screenshot below):

- If your copy of iTunes was downloaded from the Microsoft Store, it automatically updates and there is no need for you to concern yourself with the process. If an update was found (by iTunes) it will be up to date within a few minutes of starting up
- If the Check for Updates states that your version of iTunes (12.10.11.2) is the current version, that suggests that you are using Windows 7, which cannot install the latest version. (Yes, Apple's choice of words is poor, it should state that 12.10.11.2 is the latest version that will work with Windows 7.)