Commonly... and I'm just guessing here... that you might be running the camera in "AUTO PICT" mode.
... by chance have you the manual for the camera?
If you are needing one...
Operation Manuals Download : Support & Service | PENTAX RICOH IMAGING
... have a look at Page 103...
However, if you look at the top of the camera at your "mode dial" and you will see the "Tv" is one of the settings. Called the "Shutter Priority" mode, it actually means 'Time Volume' in technical speak. Turning it will switch the programmed behavior of your camera and turning it later will restore the camera back to originally set use.
Next important is the "E-dial"... this is the little wheel that can be reached by your thumb when the camera is gripped at the ready. The dial allows you to run through the different speed settings or other settings depending on where the mode dial is set.
So that after selecting the Tv mode, you'll be able to adjust the shutter times to times suggested. Feel free to test the E-dial out.