Excel has a couple of different “language layers,” and changing just the display language isn’t always enough. Here’s the full path to switch everything to English (including formulas):
In Excel, go to Arkiv → Alternativ → Språk.
Under Välj visningsspråk för Office-program, set English and click “Set as Preferred.”
Under Välj språk för att redigera, also set English and click “Set as Preferred.”
Important for formulas: change the Proofing language to English (this controls function names). You may need to install the English language pack if it isn’t already installed.
Close Excel completely, then restart your computer.
⚠️ Note: Formula names depend on the editing language. If Swedish is still the top editing language, Excel will keep using SUMMA() instead of SUM().