Viewers must opt-in to be eligible for gift memberships. Once you have opted-in, you are now eligible to receive gift memberships on any channel with gifting enabled that you have interacted with recently (for example, by watching a video on that channel). When you receive a gift, it will be automatically applied to your account, giving you access to special perks like badges and custom emojis.
If you previously opted-in for a specific channel only, you are still eligible to receive gifts on that channel. You will still need to opt-in globally to be eligible to receive gifts on other channels.
To opt in for gift memberships, you must be signed in with a YouTube channel that isn’t a Brand Account. Check if you’re on a Brand Account. Right now, channel members aren’t eligible to get gift memberships.