Change the text color of the chart title in a PowerPoint Histogram chart - vba

Question

I am trying to change the text color of the chart title of a histogram chart in PowerPoint.
Here is what I do:
var colorFormat = chart.ChartTitle.Format.TextFrame2.TextRange.Font.Fill.ForeColor;
colorFormat.RGB = ...;
// or
colorFormat.ObjectThemeColor = ...;
This works for the standard charts like line charts. But it doesn't work for other chart types like histogram, waterfall, tree map etc.
In these cases, setting ObjectThemeColor sets the text to black. Setting RGB does actually set the correct color. However, in both cases, as soon as the user changes the selection, the text color jumps back to the one it had previously.
How can I set the text color of the title of one of these charts?
I am using VSTO and C# but a VBA solution is just as welcome as long as it can be translated to C# and still work.

Answer 1

Based on what info you gave I built a histogram and waterfall chart in PowerPoint and was successful using:
Sub ChartTitleFontColor()
Dim oShp As Shape
Dim oCht As Chart
'Waterfall on slide 1
Set oShp = ActivePresentation.Slides(1).Shapes(1)
If oShp.HasChart Then
Set oCht = oShp.Chart
End If
' Do stuff with your chart
If oCht.HasTitle Then
Debug.Print oCht.ChartTitle.Text
oCht.ChartTitle.Format.TextFrame2.TextRange.Font.Fill.ForeColor.RGB = RGB(251, 5, 40)
End If
'Histogram on slide 2
Set oShp = ActivePresentation.Slides(2).Shapes(1)
If oShp.HasChart Then
Set oCht = oShp.Chart
End If
' Do stuff with your chart
If oCht.HasTitle Then Debug.Print oCht.ChartTitle.Text
oCht.ChartTitle.Format.TextFrame2.TextRange.Font.Fill.ForeColor.RGB = RGB(251, 5, 40)
End If
' Clean up
Set oShp = Nothing
Set oCht = Nothing
End Sub

Answer 2

Your code works in my test. I created two charts in PowerPoint 2016, the first one a waterfall, and the second another type. The following code changes the title color only (and text just a proof of it being changed) and nothing else. I can select the other chart and nothing changes. I could not find a bug about this in a search. Perhaps something in the remaining code is changing it back?
Sub test()
Dim myPresentation As Presentation
Set myPresentation = ActivePresentation
Dim myShape As Shape
Set myShape = myPresentation.Slides(1).Shapes(1)
Dim theChart As Chart
If myShape.HasChart Then
Set theChart = myShape.Chart
If theChart.ChartTitle.Text = "This is blue" Then
theChart.ChartTitle.Text = "This is yellow"
theChart.ChartTitle.Format.TextFrame2.TextRange.Font.Fill.ForeColor.RGB = RGB(255, 255, 0)
Else
theChart.ChartTitle.Text = "This is blue"
theChart.ChartTitle.Format.TextFrame2.TextRange.Font.Fill.ForeColor.RGB = RGB(0, 255, 255)
End If
End If
End Sub

Answer 3

This is not exactly an answer but I think you should name your object.
Instead of using
ActivePresentation.Slides(1).Shapes(1)
You can name the object.