You can set your default country, platform, and period under your Preferences tab.
Click on your profile name at the bottom left corner of the app
Go to Your Preferences
Pick your preferences using the dropdown menus. By default, you can choose to have a:
Country (all countries or a specific country)
Platform (Amazon, Apple Music, Spotify, Deezer, or YouTube)
Product type (single or album)
Display period (7 days, 14 days, 28 days, 12 months, or all-time)