How come when I create a Libreoffice spreadsheet it shows up in a new window as a Microsoft Excel document?

When ever I make a Libreoffice spread sheet it shows up in a new window as a Microsoft Excel document?

Please answer the following questions :

  1. What version of LibreOffice are you using?

  2. What is your computer’s operating system?

  3. Exactly what steps do you follow (step by step) to save your newly-created spreadsheet before you close it?

  4. What exactly do you mean by “shows up in a new window”? (A new window of which program, for example?)

There are other questions but the ones above will get us started.

I second questions @ve3oat asked, and @mariosv guess. It’s also unclear if e.g. your system has some other office suite installed, which e.g. could associate some file types with itself… which is known to happen frequently e.g. for MS Office, which re-registers both own file types, and ODF (!) to itself, without a notice or an option to disable, every time it updates with Windows Update.

In general, the question is a bright example of insufficient information which doesn’t allow others who aren’t sitting by yourself to understand your problem clearly. My advise is please read several good guides to asking good questions.

Maybe because it is saved as excel file format .xlsx not as the default for LibreOffice .ods?
It can be setup as default en Menu/Tools/Options/Load&Save/General - Default file formats and ODF settings.