If your friend has attached their real name to their YouTube account, you’ll be able to find them through the Search function. You can do this on the YouTube website or in the mobile app.  If you know your friend’s YouTube username, you can type that instead. To search in the mobile app, tap the magnifying glass icon to bring up the search box. This icon looks like a magnifying glass. Once the search is complete, a list of results will appear on your screen. On YouTube, your friend’s homepage is called a channel. If your friend has uploaded content, posted a comment, or created a playlist, they have a channel. Click “Filter” at the top of your search results and select “Channel” beneath “Type”. In the app, click the icon at the top right (three horizontal lines with vertical lines crossing through), then select “Channels” from the “Content Type” drop-down. If your friend has a common name, several channels may appear in the search results. Browse each channel by clicking the profile photo to the right of its name. Once you’ve located your friend, you can subscribe to their channel by clicking (or tapping) the red “Subscribe” button. This button appears at the top of the user’s channel.

TL;DR in Indonesian:
Tikkan nama teman pada kolom pencarian YouTube. Klik atau sentuh ikon pencarian (“Search”). Saring hasil pencarian untuk menampilkan kanal saja. Telusuri kanal teman Anda. Ikuti dan berlangganan kanal teman Anda.