How do i change the AM/PM on my T5k816 Marathon watch

Question edited to add maker.

Reset the day in the settings. My guess is that you are in the wrong year.

Months and Years having Monday the 2nd

Time and Date https://www.timeanddate.com > weekday-monday-2 Monday, March 2, 2020 · Monday, November 2, 2020 · Monday, August 2, 2021 ; March · November · August ...
https://www.google.com/search?q=timex+marathon+wr50m+manual

MARATHON® DIGITAL - assets - Timex

Timex US https://assets.timex.com > manual PDF Feb 13, 2020 - Please read instructions carefully to understand how to operate your Timex® watch. FEATURES AND BASIC OPERATION. Your model may not have all ...
19 pages

Instruction Manuals, User Guides & Downloads

Timex CA https://timex.ca > pages > watch-manuals Instruction Manuals, User Guides & Downloads. Search for documentation for your Timex ... Features: Standard analog products, including Timex Q Reissue, Marathon .

..

https://www.timex.com/watch-manuals.html
Search for Marathon - its there.

how do i decrease the year?

To set time and date:
1) With time and date showing,
press SET and hold for 2 seconds.
2) Seconds flash. Press START/STOP to set seconds
to zero.
3) Press MODE
.
Hour flashes.
Press START/STOP
to change hour, including AM (no symbol) and PM.
4) Press MODE
.
Minutes flash.
Press START/STOP to change
minutes; hold button to scan values.
5) Press MODE. Year flashes.
Press START/STOP to change year.
6) Press MODE
.
Month flashes.
Press START/STOP
to change month.
7) Press MODE
.
Date flashes.
Press START/STOP
to change date.
8) Press SET
, at any step, to exit and save settings.
With time and date showing, press SET
to switch between 12- or 24- hour time format.
Date (day of month) appears in upper part of display in Time
mode. Press and hold START/STOP
to see month, date, and year in large digits

Or go to:
http://assets.timex.com/user_guides/Marathon/W292-Marathon-AllLanguages.pdf

https://www.timex.com/watch-manuals.html

Lily, Check the attached links Timex manuals,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
How to change military time to AM PM time on Women Timex 1440 Sports Watch
http://assets.timex.com/user_guides/W15_M774/W15_M774_NA_EN.pdf
http://www.timex.com/info/watch-manuals

try this link > http://assets.timex.com/manuals/

I'm guessing that your watch is described here
http://www.walmart.com/ip/Marathon-by-Timex-Digital-Mid-Size-Black-and-Silver-Tone-Watch/38229915
(at the bottom it says model = T5K805, name is marathon)
[also on Amazon - http://www.amazon.com/Timex-Womens-Marathon-Sports-Digital/dp/B00R4XTAJ8/ref=sr_1_3?s=apparel&ie=UTF8&qid=1421449802&sr=1-3&keywords=t5k805&pebp=1421449828860&peasin=B00R4XTAJ8)

Then.look down the list for marathon in this http://www.timex.co.uk/info/product-manuals-downloads
and choose the one of the three you want. The non GPS one is very short and not really what I'd call a manual. I hope this is what you need. Otherwise contact Timex

16.January.2015

Timex Product Manuals Downloads