When building a chart that gets filtered by different User IDs using a Dropdown, more often than not you’ll want to hide the underlying User IDs. Instead, you can show the corresponding user names so that dashboards aren’t exposing actual User IDs. Accomplishing this is very straightforward in Chartio utilizing Key Value pairs!
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Once you've created your Dropdown, click the gear and hit Edit Filter. Then just make sure to drag the column you want reflected on the dashboard on the top of the Dimensions box:
Now you’re good to go!