Additional Information
Every item in an array must have all the exact same properties (colour, font, size, visibility, disabled, etc). Changing this would cause unfeasible memory increases in the sizes or LabVIEW arrays.
Consider disassembling your array and having each element as a separate control on the Front Panel. This will allow each control to have a separate label. Alternatively, clusters do allow for each individual element to have a different label, even if they are all of the same data type. This would require using the cluster functions, like Bundle/Unbundle, instead of array functions to manipulate the data.