Custom Data Labels with Colors and Symbols in Excel Charts - [How To ... Step 4: Select the data in column C and hit Ctrl+1 to invoke format cell dialogue box. From left click custom and have your cursor in the type field and follow these steps: Press and Hold ALT key on the keyboard and on the Numpad hit 3 and 0 keys. Let go the ALT key and you will see that upward arrow is inserted.