You can paste tickers into the search bar of the watchlist either one at a time or as a batch.
However, you can also import a watchlist if you have it saved in a spreadsheet file like .XLSX or .CSV. Click the up arrow button at the top of the watchlist tool.
Next, select the option to either add or replace the tickers in the watchlist. Then click the upload button, and navigate to the saved file you are trying to import.
Click on Import/Sync to complete the process.