This behaviour indicates that the keyboard layout is not set correctly. If a "+" appears when the button for "!" is pressed and the "@" sign does not work, the wrong layout (e.g. English instead of German) is probably active.
You can check and correct this:
°Windows:
- Go to Settings → Time & language → Language & keyboard.
- Make sure that German (Switzerland or Germany) - QWERTZ is active.
- Remove other layouts or switch with Alt + Shift or Windows + Spacebar.
macOS:
- System settings → Keyboard → Input sources.
- Select German and remove other layouts.
°Test:
- "@" should be on Alt Gr + Q (for German layout).
- "!" should be on Shift + 1.
It appears both in the title and in the search results. As long as there is no filtering, e.g. only CH layout is searched for, the layouts are treated equally valuable.