Does this watch really have an alarm? - Seiko SND075 Wrist Watch

You did not mention model. However, follow the procedures given in this manual. It will help you to set correct time.
Sport LCD Watch Instructions (medcentersystems.com)

Press START/STOP to select whether an alarm is referenced to the time shown in Time mode (t1) or Time 2 (t2). 4) Press SET, at any step, when done setting. To turn on/off the alarm and hourly chime, press START/STOP repeatedly. The watch will step through four combinations of alarm and chime settings.

Pull out the crown to the alarm setting position. The crown is located on the right side of the face of the watch. Pull the crown out until "AL", the alarm indicator, is shown on the watch. Depending upon the model of your Tag Heuer Aquaracer watch, you will either pull the crown out in the first or second position.

Select the hours and minuets for the alarm. Once your watch is in the alarm setting position, press the bottom right button on your watch. This will enable you to select the hours and minuets that you want to set the alarm for.

Set your alarm. To begin setting your alarm turn the crown clockwise until the desired hour or minutes are displayed on your Tag Heuer Aquaracer watch. If you happen to accidentally pass the alarm time, turn the crown counter-clockwise the get back to the desired alarm time.

Save your alarm. When you are ready to save your alarm, simply push in the crown. Once your alarm sounds, to silence it press any button on your Tag Heuer Aquaracer watch.

You should have a symbol of a bell, which indicates he alarm is "on" and the letters "CH" which means "hourly chime".
Press button at 2 O'clock position to enter the alarm mode. Press the button again and the "bell" should disappear; press the button again and the "CH" should disappear.

Now press the button at the 7 O'clock position to return to the normal timekeeping mode.

I have this watch, it think its the same one, the manual on the website didnt work for me either :D

okay

To change the Alarm
Hold mode whilst on the time section.
then start/stop changes between hour and minute, adjust changes the number.

To get off that press mode again.

To change the actual Time
Go on to the stopwatch section Hold Mode, if it shows you the alarm press mode to change to time. The seconds should be flashing, press start/stop to change between hour minute second date, and adjust changed the number.

I really hope that helped even if its a month late :D

Here are the instructions to view, change alarm time and turn off alarm:

From normal time display:
Press MODE once to display stop watch.
Press MODE again to change alarm time.
Press MODE again to change time.

From normal time display:
Press RESET once to display current alarm time.
Press and hold RESET then press START to turn on and off alarm (watch for alarm symbol on top left)
Press and hold RESET then press MODE to turn on daily alarm vs one time (watch day marker lines at the bottom)
Hope this helps.

Normal 0 Here is the watch movement manufactures instruction .pdf.
RONDA startech Cal. 5130.D
http://www.ronda.ch/pdf/ba5130.De.pdf

Just answered this question for someone else so I thought I would just copy and paste my response.
Now sure if you are still looking for a solution or not but just came across your problem. The lower right-hand button, the one used to turn the alarm off and on, can actually be pulled out to set the alarm. Pull out the knob, adjust the alarm time, push back in and push one more time to actually set the alarm. Hope this helps.

After putting the caseback back on, press all four buttons simultaneously to reset the watch. This worked for me.

Here is a link for the manual for your watch. I could explain how to fix your problem but thought it would be easier with the manual and pictures. If this fixes your problem please rate. Thanks. Good luck in school! http://ftp.casio.co.jp/pub/world_manual/wat/en/qw2747.pdf