Two time signatures in first bar

If you right click the time signature, you can access Time Signature Properties, which lets you set the appearance of the time signature. Not sure it will give you exactly the formatting you want, though. So you could also add the second time signature one number at a time from the Symbols palette (press "Z" to display).

Since 3/4 and 6/8 both have 6 8th notes the beaming will follow whichever beaming is defined for the time signature you start with. You will need to fix beaming in measures with the other time signature.