Unfortunately, Excel itself doesn't offer a built-in way to fully customize chart tooltips. However, there are a couple of creative workarounds you can use to achieve a more interactive data exploration experience:

1. Using a Helper Column and Text Box:

* Create a Helper Column: Add a new column to your data table specifically for crafting the desired tooltip text. You can use formulas to combine relevant data points from your existing columns into a user-friendly format for the tooltip.
* Format Text Box: Insert a text box (under the "Insert" tab) on your chart and format it for aesthetics (font, size, color, etc.). Give it a descriptive name for easy reference later.
* VBA Code for Dynamic Update: Write VBA code (This requires some programming knowledge) to link the text box content to the specific data point being hovered over on the chart. The code would essentially reference the helper column cell corresponding to the selected data point and populate the text box with the appropriate tooltip information.

2. Using Live Picture and Conditional Formatting:

* Create a Chart Image: Create a separate chart with the desired tooltip layout and formatting (including text boxes with placeholders for data). Copy this chart and paste it as a "Linked Picture" onto your main chart.
* Conditional Formatting on Main Chart: Apply conditional formatting to the data points on your main chart. Set the formatting to trigger a change in cell fill color (e.g., very faint highlight) when the mouse hovers over that data point.
* Link Picture to Data Point: Right-click on the linked picture from step 1 and choose "Format Picture." Navigate to the "Fill & Line" tab and choose "Picture fill." Select the cell containing the faint highlight color from your conditional formatting in step 2. This essentially creates a "clickable area" over the data point.
* Change Linked Picture Source: When a user hovers over a data point on the main chart (causing the conditional formatting to activate the highlight color), the VBA code linked to the linked picture would be triggered. This code would then dynamically update the text boxes within the linked picture with the corresponding data from the helper column, effectively creating a custom tooltip.

These methods require some technical knowledge but offer more control over the tooltip appearance and functionality. There are also online resources and pre-built VBA code examples available that can be adapted for your specific needs.

Additional Tips:

* Consider using clear and concise language in your tooltips.
* You can incorporate data formatting (e.g., percentages, currency symbols) within the tooltip text.
* If using formulas, ensure they update correctly when the chart data changes.

By implementing these techniques, you can enhance your Excel charts with informative and interactive tooltips, leading to a richer data exploration experience.