If you would like to apply custom colors to all of your charts on a Dashboard, see our documentation on creating a Theme.
If you would like to apply custom colors to one specific chart, see the instructions below.
From your Dashboard, hover over your chart to reveal the gear icon in the upper-right corner. Click it, and select Edit Settings from the dropdown menu. (You can also access the chart settings by choosing Edit Chart Data and clicking the Chart Settings button in the Data Explorer interface.)
In the Chart Settings, scroll down until you see the Use custom colors checkbox. Check it, and your datasets will appear with their default corresponding colors.
Click on a color to open the color picker, and choose the color you'd like. You can also input hexadecimal color codes if you'd prefer. Click Select when you've chosen your color, then click Refresh Chart to view your changes.
The colors will be tied to each specific dataset, so if the ordering in your chart changes due to the data changing, the color you associated with Login, for example, will always stay associated with Login. However, the color will reset if you change the name of Login.