HELP me before they run away!

So, I am at a loss as to what to do now with our front and back doors. They are lever knobs and the boys can open them. They can also reach and unlock the deadbolts. So...they could potentially get out of the house antyime they want which worries me if I have to run to the bathroom or run upstairs to put laundry in or something. The toddler locks they have for lever knobs won't fit on these doors but on the doors they do fit on, they know how to unlock them anyway.
Any suggetions besides putting another dead bolt on the door up higher?

 

When this happened to us, in the dead of winter, we put a chain lock up high so that they couldn't reach them and unlock/open the door. I have a SIL who put an additional door knob up high, so that in order to open the door, BOTH door knobs needed to be turned. She did it that way because one person left early for work and the door had to be locked after that person was gone.

 

I was going to suggest the chain lock up high.
Good luck!!

 

Ages ago with my middle son we installed swing bar locks very high on the front and back doors. It work great with him and now my twins 5 yrs later. I also love the security at night! Here's a pic link of something similar: http://s7.kmart.com/is/image/Sears/9990000051255711?hei=500&wid=500&op_sharpen=1

 

We are considering swing bar locks too, though I'm hoping that the novelty of their new-found ability to open the deadbolt and the doorknob lock will fade after a while. I'm not worried about them actually running away, but if they see someone walking by that they want to say hi to, they're likely to just bolt out into the yard without asking first.