OK button.
Once you complete the steps, you can save the customization file and then use it to restore the settings in the future on the same device. Or you can use the file to import the settings on another computer.
If you have an older version of Office, you are not taking advantage of all the suite features. If you switch to a Microsoft 365 subscription, you can always upgrade to the newest version of the most popular suite of apps to access the latest features for free, and you get many other benefits, such as sharing the account with up to six people and every user gets 1TB of OneDrive cloud storage.