Hi Ning,
There is not a way to highlight a text field using a formula or function natively in Quick Base. It is possible to make a field required though, so it cannot be left blank. The record will not be able to be saved unless the fields are filled in. Using form rules it is also possible to make a field required only under a specific set of circumstances. Such as Phase is required when Project Type is Planning, etc. Otherwise you can also make a formula field next to it that gives them a message or warning to prompt the user that the manual entry field is needed. I hope these suggestions are helpful Ning.
