Erratic display and cursor movement

The problems are mainly: cursor freezes, screen won’t accept edits, space bar freezes, blue border / frame appears on my word documents, and screen bounces around after I type or cut & paste edits. Using Tab button causes cursor to jump to controls at the menu bar below the screen (e.g., word count, language, Focus). Sometimes the Tab key closes a Word document and brings up some other, random app.  

My equipment: MacBook Pro laptop with 1.4 GHz Quad-Core Intel Core i5, running macOS 14.6.1 Sonoma, mirrors to LG Display.  Using DuckDuckGo. Running MS Office Home & Business 2021. Using Bluetooth Logitech MX mini keyboard (for mac).