Why is there a limit to minutes when my videos are each less than 10 seconds?

Hi I have 3 credits left that I want to use - but there is now a time limit which has been added to my account? Each time I generate a video my time limit goes down by 1 minute? But the video I am making are all less than 10 seconds long? Why each time I make a video of less than 10 seconds? Does it deduct 1 minutes from my account? And now I have 3 credits that I want to use - but my account is blocked because even though I have 3 credits left to use - the minutes have run out? All videos that I have made are all less than 10 seconds long? So why is 1 minute being deducted for each video? Before I just had credits to use there was no time limit? Very disappointed with the time limit - when I am being charged 1 minute for a 3 second video ?