Thanks for your questions, here I am trying to write your answer shortly. and I will give you a short video which will help you for better understanding how to get the custom URL of your channel .

Get a custom URL for your channel

Please follow these instructions to get your custom url. To get custom URL, you must need to visible for custom URL of your channel. If your channel is eligible, you can give fans an easy-to-remember web address, called a custom URL, for your YouTube channel. This is called a custom URL and looks like https://youtube.com/knowledgeworldbd  and youtube.com/c/yourcustomname.

You can choose a custom URL based on things like your display name, your YouTube username, any current website URLs that you have, or the name of your linked website (all subject to availability).

When sharing your custom URL, you can change its capitalization and accents any way you want. For example, both youtube.com/c/yourcustomname and youtube.com/c/YourCustómNámé would send viewers to the same channel.

Remember, You can’t change a custom URL after creation. However, you can remove the custom URL from your channel and claim a new one if you want to change it.

When you claim a custom URL on YouTube, you no longer also get a Google+ URL. Learn how to claim a custom URL for your Google+ profile.
Claim a custom URL for YouTube
You can claim a custom URL if you meet the general eligibility requirements. Follow the steps below to set it up.

Custom URL Eligibility requirements

To create a custom URL for your channel, your account needs to:

* Have 100 or more subscribers
* Be at least 30 days old
* Have an uploaded photo as channel icon
* Have uploaded channel art (In general, a YouTube channel may only have one (1) custom URL and custom URLs cannot be transferred or assigned to anyone.)

How Set up a custom URL for your channel
If you’re eligible for a custom URL, you’ll see a notice in your advanced account settings, get an email notification, and may see a notification in your Creator Studio dashboard.

Before you start: Keep in mind that you can’t change a custom URL after creation, including adjustments to the capitalization, accents, or diacritics.

* Sign in to YouTube.
* Go to your advanced account settings by clicking your icon in the top right
> Settings or . Then click Advanced under your account name.
* Under “Channel settings,” select the link next to You’re eligible for a custom URL. You’ll only see this link if your channel is eligible.
* In the “Get a custom URL” box, you’ll see the custom URL(s) you’ve been approved for. You can’t change the part in the gray box, but you may need to add a few letters or numbers to make the URL unique to you.
* Carefully read and understand the “Custom URL Terms of Use” and select the box to agree to them, then click Change URL.
* Once a custom URL has been approved, you can’t request to change it, so make sure this is the custom URL you want before clicking Confirm choice.
* Once you have a custom URL, your audience can reach your channel by using that custom URL (e.g., youtube.com/yourcustomname, which will take viewers to your channel homepage).

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Watch this video for more clarification:

Thanks.