Arduino FIFO queue for with potentiometer values and 7 segment display
Without seeing the code it is bit difficult to help. Please edit your answer and include the relevant parts of the code, otherwise we will end up (re)writing your code for you.
Hint: why not, when you detect a change in the pot, take the new reading, and then count down/up slowly (at the rate that you desire) from the currently displayed reading to the new measured reading - using a for loop, which contains a delay()? With each iteration of the loop you can display the new value. Easy!
However, this sounds like a terrible idea
Note that your code won't do anything else whilst the display is incrementing and decrementing, using this method. So, if you were to spend a lot of time twiddling with the knob, then the code wouldn't get much time to actually do any real work, apart from displaying the updated value.
In order for your code to do real work, whilst displaying the new updated value, you would either need interrupts, or integrate the display updating procedure into the loop(), such that each iteration of the loop() updates the display (or upon each n iterations of loop(), as loop() will probably be looping to quickly. You will probably need to use millis()).
NOTE: From a UX aspect, although it all sounds very 1960's-James-Bond-evil-guy-equipment, the whole notion of the displayed value slowly following the actual location of the knob sounds, at best, extremely infuriating, if not down right dangerous (depending upon the context). Human feedback should be as fast as possible. Else the user will constantly be turning the knob to reach the value that they which to achieve, when in fact they have already passed that value, and may be over compensating, and it is just the fancy display graphics that is showing the wrong value.
Assuming that the knob is controlling something else (actuator, motor, heater, etc.), and not just a pretty display in itself, unless, you are actually outputting the delayed displayed digital value, and not the knob's actual current analogue value, I would seriously recommend against doing this.
I may be wrong, and it would probably require a separate question on SE.UX, although, I would imagine that it has been asked already.