I don't know of a way to connect the Alternate Measures and a Title.
But, here's a cheeky workaround you could use.
Make your Bar chart to be a 'Horizontal ' bar chart with the x-axis position set to 'Top'. This will ensure that your users don't have to hunt-for or guess about the metric being displayed, it'll be there at the top, in their immediate field of view.
No It's not possible to do so,
But try this, see the attached App.
You can use the Styled List extension instead of the actual filter object:
Example of use:
Field timeframe containing 3 values. I want to have 'annuel' selected by default when I open the app
Result: when I open the sheet :
I find it selected: