The issue is with your on created event, which I assume is true on start of layout, that's why I mentioned to disable events to check where the problem is. On created also targets sprites created on the start of layout, even persist objects are created again, so it's setting everything to black I assume because that event is true when you go in. You could fix this by adding a condition, on blobdraw created and only if the string instance variable is "" then set the color.