Please read more about the tips and tricks of the Flex properties in the header builder here and here.
Having said that I suggest that you add a Bar and 2 containers inside that bar. Set the bar to be in row mode.
Then go to the second container which should have the button and stuff and set it to be row too. So all the buttons and stuff will be inline, but make sure that the container Wraps element and set a limited width for the container.
That will force the row based elements to go to the next line and have the stacked view. Play with the width of the container to have it fixed as you like.
For the mobile version, I suggest that you have a separate bar with all the needed information and layout using the hide during breakpoint option.