Different model phones (and it also depends on which version of CUCM you are using) have their softkeys governed by either a "Feature Control Policy" or a "Softkey Template". The Feature Control Policy is/was invented to be used by phones with feature hardkeys for Hold, Transfer, etc.
To see whether your phones use Feature Control Policy or Softkey Templates by default, you can look at "Enterprise Phone Configuration" and look for the field "Softkey Control".
Now, both the 69XX series and the 78XX series have feature hardkeys, so I would expect that they would both be governed by Feature Control Policy by default. But I have run into combinations of phones and CUCM versions where certain models of phones that have feature hardkeys will use a Softkey Template that has taken the feature hardkeys into consideration (like "Standard User with Feature Hardkeys") and some still use Feature Control Policy.
If the Enterprise Phone Configuration for "Softkey Control" is set to "Feature Control", you can test to see if changing that to "Softkey Template" will fix the problem by:
1) Create a Common Phone Profile with the Softkey Control set to Softkey Template
2) Apply that Common Phone Profile to one of your 7841 phones and reset.
