Welcome to the forums @Robert Wahl,
Do you mean the thumbnail size ? If so, go to the burger menu, the three horizontal lines in the upper right corner. Click on it and you get the option to change the thumbnail sizes from Small, Medium, and Large.
I know trying to lengthen the Panels are a big pain, trying to get that double-headed arrow. How about dragging the Layers Panel out, then you can make it as long as you want.
Do you know you can Customize the Studio and Save them? So move things around, get them how you need to work, then in the View menu, scroll down to Studio Presets>Add Preset.
