1) Yes, you can control what displays in the pop up box. First, name your columns such that they make sense to users. If "ProductDescription" is meaningless to them, name the field "Product Name" or something. You CAN override this by giving the column a label in the chart itself, but I would avoid that, as you generally don't want multiple names for the same column. Pick a good name, put it in your script, and stick with it. As for count(distinct Email), add a label to your expression, like "Number of Email Addresses". When you give an expression a label, QlikView will show the label instead of the expression in the pop ups.
2) It is not an update indicator. It is a selection indicator. And it doesn't show you a green dot on the CURRENT sheet. You're on the sheet, so you should be able to see that you've made selections on that sheet. The green dot only appears on OTHER sheets, the ones that aren't currently active, if there are fields selected on the other sheets. It doesn't matter if your selection changes data on the other sheets. It only matters if those sheets show that selection in a list box or multibox. I'm not sure that's how I'd have designed it, but I believe that's how it's working.
3) You cannot force a log scale if any of the data points are zero. A zero data point on a logarithmic scale would be infinitely far below your monitor. It cannot be displayed. Rather than fail to display your data, it switches the scale to allow the data to be displayed. I suppose one way to force a logarithmic scale would be to change the expression to convert zero to an arbitrarily small value or maybe null.
4) Yes, you can display just the R-squared value, but not with the checkbox unfortunately, so it gets a little complicated. Go to the Presentation tab and click on the Add button next to "Text in Chart". It will pop up a little box to enter the text you want to display. This allows you to enter a formula to compute the R-squared value. Let's say that our chart is showing sum(Sales) with a dimension of Month. The R-squared value is this:
pow(correl(aggr(sum(Sales),Month),Month),2)
But you'll probably want text with it, and you'll probably want to format it. So enter something like this in the text box:
='R-squared = ' & num(pow(correl(aggr(sum(Sales),Month),Month),2),'#,##0.00000')
Now, it looks like it wants to put the text in the upper left of the chart. To change that, select the chart and hold down the control and shift keys. Red boxes should appear around some of the chart elements, including your new R-squared text. You can drag and drop and resize the boxes.
I don't think you can directly control the color of the trend line. QlikView really wants it to match your expression. But you can create your OWN trend line as an expression, and then you can color it any way you want just like any other expression. Another advantage is that it now lets you get the pop up information for the trend line itself, not just for your data. For my example, the trend line expression would be this:
linest_m(total aggr(sum(Sales),Month),Month)*Month
+linest_b(total aggr(sum(Sales),Month),Month)
The attached example demonstrates both of these things.
