I don't have a manula for my jwx31 and I can't set the timer

Copy following links for TB178 timer:
http://waterheatertimer.org/How-to-wire-TB118-TB178-timer.html
http://waterheatertimer.org/How-to-set-timers.html
The override button is temporary and regular schedule resumes at next tripper. So basically the override can be in any position.
Add a comment and describe timer in detail so identification can be made.

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If the timer does not keep the time of day then it is faulty and needs to be replaced.
Timers have adjustable tabs to turn the timer on and off at a set times of day.

That timer is not identified:
Copy following link to see variety of timers that might match your timer, and then download same-similar manual:
http://waterheatertimer.org/Woods-timers-and-manuals.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following link for possible photo assistance of tripper installation:
http://waterheatertimer.org/images/WH-lever-005-500.jpg
http://waterheatertimer.org/Intermatic-timers-and-manulas.html#pool

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Timer is not identified.
Open following link to identify timer and download manual.
http://waterheatertimer.org/GE-timers-and-manuals.html#zilla

1) If you have zilla digital power strip, there is no reset button.
It appears you can reset timer by removing small battery located on back of timer.
Battery serves as a back-up for timer settings, and display will not show without battery.
Most battery-operated timers that do not have reset button are reset by removing battery.

Some battery operated timers retain programming forever even if battery is removed for months, and then programming is still there when new battery is installed. However this type of timer has a reset button, but zilla does not.

2) A second way to clear programming is to press PRG button to review each program, and set each program to another time. I don't know if this will work since you can't 'zero' out the settings.

add one cup of distilled vinegar and let set overnight. brew the next morning to descale

you can find that info here http://waterheatertimer.org/How-to-set-timers.html

You can download your instructions here:

R673CT Digital Water Timer Installation Manual

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I'm not sure what timer you have.
Programmable timers are made so you press-and-hold the button, and then display goes up through the numbers as you describe.
I test timers, and have not seen the fault you describe. 4-6% of timers arrive defective.
However you have several timers that do the same thing.
If you press the button once, then the first number shows, press button again and next number shows.

If your timer is going up through the number with one push of the button then try resetting timer.
I cannot identify your timer to know what the reset steps are.

Also, many timers you push the + button to go up through the numbers, and push the - button to go down through the numbers > try both buttons since one may be made for individual selection and other for acceleration through all numbers.
If timer operates on 120V, perform circuit analyzer test on the circuit to eliminate electrical as source of problem.
If this is a hard-wire timer, carefully review of wiring.

If you find the specific source of problem, add a comment.

Securitron makes DT7 programmable timer
To see image and identify timer:
http://absupply.net/securitron-dt-7-prime-time-digital-timer-6071.aspx
On-line manual shows on page

Intermatic shows DT300 series has been discontinued by Intermatic:
This timer also sold as Woods 59203 and GE 15091
To see image of timer:
http://waterheatertimer.org/Woods-timers-and-manuals.html#59203

Intermatic shows DT17 timer:
http://www.intermatic.com/~/media/files/intermatic/products/instructions/timers/dt17c%20-%20english.ashx
DT27
http://www.intermatic.com/~/media/files/intermatic/products/instructions/timers/dt27c%20-%20self%20adjusting%20-%20english.ashx
DT121

Usually you have to press in the first 2 buttons whilst you set the clock time then make sure MANUAL cook is selected