Remove formatting for all cells

How can I remove individual formatting from all cells? When pressing Ctrl+M to remove formatting when having multiple cells selected their individual format stays the same. With individual I mean right clicking on a single cell and formatting it e.g. to englisch language

CTRL+M resets all cells to the default cell style defined in your default template (which in general is Category Number and Format General and Language as per your Locale setting in LibreOffice options). Thus the question is not clear (at least form me). If this doesn’t happen on your LibreOffice installation (you did neither provide your LibreOffice version nor your operating system), I’d suppose a problem with your user profile or in the worst case a bug.

Quoting @anon73440385: "CTRL+M resets all cells to the default cell style defined in your default template…"
This isn’t quite correct.
-1- (trivial) The cells must be selected. Ctrl+A will do. If more than one sheets are selected via their tabs at the time this will afflict all of them.
-2- (substantial) Neither the assignment of named cell styles to cells nor the properties/attributes defined for these styles are afflicted by Ctrl+M.

Quoting @NoNameHD: “When pressing Ctrl+M to remove formatting when having multiple cells selected their individual format stays the same.”
This is definitely not correct.
If not your local settings messed up the Ctrl+M shortcut, your you are working with a strange UI or locale using a different shortcut, Ctrl+M must remove direct formatting from all selected cells.
You need to look for:
First: Formatting done by assigning named cell styles.
Second (if the first step didn’t clear up the issue): For a corrupted user profile.

@Lupp -. nitpicking: OP stated individual formatting from all cells and from my understanding named cells styles is a contradiction to individual formatting… but may be I’ve confused with direct formatting

@anon73440385: Of course I feel sure you knew the facts. My reason to post that comment was that it expressly included the phrase “…resets all cells to the default cell style defined in your default template…” which may be misleading - at least for an unexperienced user. And by someone not knowing you, it might be read as “also reset to ‘Default’ cell style if a different named style was applied”.
Anyway I didn’t intend to be nitpicking, and I included the (imo) clarifying “quite”.
Probably another case where we should stop to be stingy on the personal level. If specific ways to talk about facts are nitpicking or not may be decided by the questioner and other visitors to the post. They are welcome.
Anyway I want to assure you my high appreciation.

Anyway I didn’t intend to be nitpicking

No, no, no, sorry for the misunderstanding - I meant my oncoming comment is “nitpicking”. Your comment is absolutely correct and as precise as always. Again sorry …

Sorry to have misunderstood you.
Glad to find things smoothed.