Sequence Render In to Out resizing clips

[#1]

Sorry if I am not using the correct terminology.

I am putting together a video which is a mosaic of other videos resized to fit together on the screen. I'm using 16x9 aspect ratio. After putting several clips in my sequence, the timeline show yellow and the playback gets choppy. I then use Sequence->Render In to Out and the timeline bar is now green. However, all of my video clips are squished, looks like to 4x3 ration. If I click and drag one of the clips, everything snaps back to 16x9, but the timeline bar is now yellow again.

How do I avoid this temporary squishing of my video clips?

[#2]

Sorry if I am not using the correct terminology.

I am putting together a video which is a mosaic of other videos resized to fit together on the screen. I'm using 16x9 aspect ratio. After putting several clips in my sequence, the timeline show yellow and the playback gets choppy. I then use Sequence->Render In to Out and the timeline bar is now green. However, all of my video clips are squished, looks like to 4x3 ration. If I click and drag one of the clips, everything snaps back to 16x9, but the timeline bar is now yellow again.

How do I avoid this temporary squishing of my video clips?

[#3]

Maybe you can try knocking down the playback resolution in the program monitor. There is a button that says either full or a fraction.  If you use a smaller resolution hopefully the playback will work at an acceptable level without having to render.

[#4]

There are so many buttons and panels, I don't see the button you are referring to. Can you give me more details on where I can find this button?