A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
What I posted is worksheet event code.
Right-click on the sheettab and select "View Code"
Paste the code as is into that module.
Return to the sheet and make sure merged cells are formatted to wrap text.
When you type text into a merged cell then hit Enter the autofit will take place.
If you already have text in a cell you can F2>Enter to trigger the code.
Gord