const config = ref({
 // ...rest of your config
 chart: {
 grid: {
 labels: {
 yAxis: {
 formatter: ({ value }) => {
 return Math.abs(value)
 }
 }
 }
 },
 tooltip: {
 customFormat: ({ datapoint }) => {
 let html = "";
 datapoint.forEach(d => {
 html += `<li>${d.name}: ${Math.abs(d.value)}</li>`
 })
 return `<ul>${html}</ul>`
 }
 }
 },
 line: {
 labels: {
 formatter: ({ value }) => {
 return Math.abs(value)
 }
 }
 },
})