For several decades tapping Cmd+F would open a Find dialog box in Word. With Word 2011 and later, this keyboard combination switches the cursor to a search field somewhere in the main interface. This is very clumsy, especially if you want to subsequently switch to replacing text.
The solution provided here is as follows:
Click Tools > Customize keyboard, then under the Categories heading select Edit and then in the Command field next door select EditFindDialog.
Jump down to the Press New Keyboard Shortcut field, and tap Cmd+F. Then click the Assign button, and OK.
From now on tapping Cmd+F will open the Find dialog box.