Could be the setting on your VCR...there's usually EP, SP and SLP. SLP is super long play which allows you to use the full amount of the tape, but if you're using one of the other two, the VCR records better quality for less time. Try to find a way to change this and your problem should be solved!

how can i change the option without a remote control?

Ummm... do ya have like a little compartment on the front of your VCR? Mine's probably totally different from yours, but there's about 6 buttons(including rec.) Try pressing each one... lp(loug play)/sp(short play) should be there, when you've pressed the right button either "LP' or "SP" will come on on ya VCR screen...
If ya think you've pressed the wrong button, and it's kinda gone wrong, just turn the VCR off, and back on again...
And if you have no clue as to what I'm on about I apoligise:p