I dont now how i can change de week date - Rolex Day-Date President 118238 Wristwatch

http://d-msh.com/page/vestal-de-novo-manual

unfortunately this is how there made they work on ratchets inside the watch and can't cope with all the functions at once.
http://support.casio.com/en/manual/009/qw4358.pdf

it can only set by turning the time for 24 hour using the crown the day of the week changes every 3 AM, i hope i had helped you.

Your watch is 12 hours out of step.

The date changes every second time the hour hand passes 12 O'clock.

Your watches' second pass is at midday instead of midnight, so to make it operate correctly, you need to wind it on 12 hours. The date will then change at midnight.

You are very observant! Timex watches don't have a way to adjust the day.
However, if you turn the hands clockwise you will see the day advance.
So, heres the secret, follow exactly:
1. Turn the hands until the day of the week shows the day before. If today is Wednesday then turn the hands until the watch shows Tuesday
2 Adjust the date to the day before. If today is the 17th then adjust it to the 16th
3. Now pull the crown all the out and and advance the hands until the date changes to the correct date, 17 in this example. This happens at midnight. Continue the movement in a clockwise direction for a few more hours and you should see the day change to the correct day.
4. Now continue to move in a clockwise direction until you have the current time. Remember that your date/day changed at midnight so if the current time is after lunch(noon) you must continue past noon to get to the correct time. If you don't do this correctly your date will change every day at noon instead of midnight.
If you don't succeed the first time, try, try again! Good luck, Michael, Watchmaker to the Stars!

As per the instruction PDF that I just read, the day of the week only changes with each 24 hour rotation. Therefore to change it, you might pull the crown out all the way and wind it through every hour in each day until it advances to the day you want. Then set the correct time. Push the crown in one notch to the second position and wind the dates forward until it stops on the one you want. It doesn't appear that going backwards for either the time (for day of the week) or date works.

mcdevito75 here, The stem has 2 positions, Carefully slip a fingernail under the stem and lift, it may take a few trys to get used to it, in this first position you should be able to set the DATE very easily and Maybe the DAY of the wwek also, turn the stem 1 way to change the DATE and the other way For the DAY of the week., Let"s figure you can only set the DATE in this first position, First thig to do is set the DAY of the week, go thru the watches 24 hour cycle and set the DAY to 1 DAY before the DAY you need, now in that first position of the stem, set the DATE to 1 DATE before the DATE you need, now in the 2nd position we all know pull the stem out to set the time of day, go thru the 24 hour cycle to bring up the DAY of the week and DATE you need. Now your watch is set and will change on tome at around mid-nite.

Most watches have a stem that you pull out to set the time. The little knob on the end of the stem is called a crown. For a day/date watch, there are two clicks. The first click when you pull out the stem is the day / date setting, the second click sets the time.

When you are on the first click, twisting the crown one direction changes the day of the week; twisting the other direction changes the date. If yours has only the date, it could be either direction depending on the manufacturer.

hi
never change week or date when day is on "sun" or "mon" also never change date or week or day when time is between 9 pm and 5 am.
to change day, move time back and forth between 10 pm and 2 am.
moon will change only after 24 hr round (not during quick day change)
hope this helps
eli

i wind the clock hands forward until the calendar date and week day changes and then i re-wind the hands until it comes to the correct time. when i re-wind the hands, the week day goes back to the correct date and the calendar date does not go back by one day. i don't know if this is the "correct" way to do it, but it works.