[Ethereum] How to select a different Metamask address when using Uniswap

You can disconnect a Metamask account from a dapp by clicking on the three dots menu on the top right (next to Account NN).

Select "Connected site" it will show a dapps list that were authorized to use the current account. You can remove the dapp from the authorized list with the trash can icon.

To authorize an account to use a dapp you have to select an already authorized account, then switch to the unauthorized one, a popup should appear asking for confirmation.

The solution will depend a little bit on your front-end. This is how I did to cover your requirements with React in TypeScript:

    React.useEffect(() => {
       const checkConnection = async () => {

           // Check if browser is running Metamask
           let web3: any;
           if (window.ethereum) {
               web3 = new Web3(window.ethereum);
           } else if (window.web3) {
               web3 = new Web3(window.web3.currentProvider);
           };

           // Check if User is already connected by retrieving the accounts
           web3.eth.getAccounts()
               .then(async (addr: string) => {
                   // Set User account into state
               });
       };
       checkConnection();
   }, []);

When Users connect to the web page, I check if there is a web3 plugin in browser and try to retrieve the accounts. If I get any result, it means the User is already connected to Metamask and don't need to trigger any pop-up to connect.

If the User is not connected to Metamask, then you can trigger the pop-up by pressing the button you mentioned, and you will execute a similar code but including await window.ethereum.enable();

If you are not using React, then you just need to execute this function the first time you load the page and skip the useEffect method.