Trying to set my watch and can't find the manual, Casio Model MMA-200 W, with 343 on the back as well.

On the Casio website, this model 6054 isn't recognised. With the module number (you'll find it in a small rectangle on the back of the watch case) you can download the manual for your watch here:
Timepieces Watches Manuals CASIO

You can get instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals",
watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box

You can get instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals",
watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box.

See the web page for instructions on where to find the watch number.

You can get instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals",
watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box

I had a casio and the method was; press the mode button until the display says "HS", then press the 2 or 4 o'clock buttons to adjust the hands to match the digital time; then press mode button until normal operation is achieved.

My watch was a different model to yours, so if this does not work, then you can get
instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals",
watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box

Set your city to DEL (Delhi).

If you haven't got instructions on how to do this, you can get
instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals",
watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box

you can get
instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals",
watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box

I assume that you don't have any instructions?

If so, you can get instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals", watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box

Click on "search" and the download your instructions.

If you don't have the manual, You can get instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals", watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box

Click on "search" and the download your instructions.

http://world.casio.com/wat/download/en/manual/

Use the four numbers on the back of your watch and you will have a PDF version of your instruction manual.

Hope this tip helps.

R/
David