The video system of your TV is NTSC, so video input should also be NTSC. If video input is PAL, you will usually get a hazy black & white picture that rolls vertically.
Your DVD player is capable of NTSC or PAL and can convert video sources from NTSC to PAL and vice-versa.
System selections of your DVD player are NTSC, PAL and AUTO. The default setting is AUTO, which means that an NTSC source will be output as NTSC, and a PAL source will be output as PAL.
You have to change the DVD player's system setting to NTSC. Your manual has instructions for changing the system setting.
You will have to use the player's buttons, not the buttons on the remote. Start with standby mode, press and hold forward button, then press power button to turn on. Changes will cycle through PAL, NTSC and AUTO.
When the DVD player is set to NTSC, it will always output in NTSC. An NTSC source will be output in NTSC, but a PAL source will first be converted to NTSC by the player internally, then output to the TV in NTSC.