I presume you are referring to this thread:
I'm guessing that you have the x-axis configured as "category" rather than date or a value. That means you need to use,
{name}: [bold]{valueY} {categoryX}[/] cases
The chart component is based on AM Charts and you can find details on options here:
https://www.amcharts.com/docs/v4/concepts/formatters/formatting-strings/
Tip: use `a pair of backticks` to format your code on the forum. It will then appear like this: a pair of backticks. For blocks of code put three ``` at the start of the block and another three at the end - or select the code and press the </> button.