Hello ah_nico,
Thank you for posting this case in Microsoft Community!
Based on your description: How to change by default folder view? I would like to cooperate with you working on this case. To clarify this case, are you using New Outlook for Windows orClassic Outlook for Windows? If you are using New Outlook, you may go to View>Densityand set as Roomyoptions as by default folder view. Here is the capture as reference:
If you are using Classic Outlook for Windows, please check this article as reference Create, change, or customize a view - Microsoft Support which help you to change by default folder view. Here are the steps as reference:
**Note:**If you want to start from an existing view, in the Manage All Views dialog box, select <Current view settings> and then select Copy.
- Enter a name for your new view, and then choose the type of view.

- Under Can be used on, accept the default setting of All Mail and Post folders or choose another option, and then choose OK.
- In the Advanced View Settings: New View dialog box, choose the options that you want to use, and then choose OK.
- To use the view immediately, choose Apply View.
Hope the above workaround would be helpful. If you need further assistance, please feel free to let me know, I will keep assisting you.
Your understanding and patience will be appreciated.
Thank you!
Microsoft Community Moderator