Excel - CSV files do not open correctly delimited

https://kb.paessler.com/en/topic/2293-i-have-trouble-opening-csv-files-with-microsoft-excel-is-there-a-quick-way-to-fix-this

This happens because the regional settings of the machine is set to use the ; as the default delimiter instead of ,

Solution: Change the Regional and Language settings  

• go to Start | Control Panel | Regional and Language Options
• Click Additional Settings
• For Decimal Symbol, enter a dot: .
• For List Separator, enter a comma: ,

OR

Add an extra line to your CSV file to tell Excel what the separator is.
Add the following line to the top of your CSV file:

sep=,