Polkadot-JS UI allows you to interact with different blockchains: Polkadot, Kusama, and many others. It is theoretically possible to use one account on different chains; however, we do not recommend it as it may lead to confusion. 

We recommend that you restrict your account to only one network. That is why Polkadot-JS UI gives you an alert for any account that is available on all networks.

How to Restrict your Account to One Network

In the Polkadot Browser Extension

1. Click on the Polkadot browser extension next to the URL bar to open it.

2. Click on the three dots next to your account, and pick the network from the drop-down menu instead of "Allow use on any chain":

4. A colorful tag with the network's name will appear next to your account. Your account now will only appear when you are connected to the chosen network:

Depending on the network, you may also see your account address and identicon change.

On Polkadot-JS UI

1. Navigate to the Accounts page and switch to the network you want to use.

2. Your accounts added directly on Polkadot-JS UI will appear under "Accounts," and you will see a warning sign next to them if they are available on all networks:

2. Click on the three dots next to the account, and enable the "Only this network" switch:

3. The warning sign will now disappear, and the account will only appear on the Accounts page when connected to this network.