Why do I feel like I have no control over my four year old?

I don't mean control maybe that was a bad way to phrase. I guess well she doesn't obey at all. I have a one and four year old daughter. She wakes up 7ish and breakfast is ready. She eats very good. Then she has activities. Reads a book or colors. Sometimes I will allow to watch Nick. So as I tend to my other daughter..change clothes or bathes..which I bathe her sister in the kitchen sink. I have her sister very near by and she always seems to be doing something dangerous. Like getting on top of the couch or chair..trying to reach things that she shouldn't be.. I know she is just a child. And some things I let slide. But for the most of it she understands what she shouldn't do but yet she still does it and constantly. I guess that is where my patience tends to go. I tried the time outs, taking away her toys, talking to her at her level. She will tell me she's sorry and she will behave for like two hours and ten start up again. And I make time for her. I sit down and read to her or we will sing and dance. It's just that I feel like she gets out of hand way to much. Every time I need to wash, cook, clean..like every time I am away from her...let it be 5-10 minutes she makes a mess or almost gets hurt with her trying to be mischievous. Ugh what to do. I do not believe in spanking or yelling. I love my baby girls very much. Please give me advice/