This guide will hopefully server as the ultimate list of controls to use in the Golf It! level editor.
If you have found another control that is not listed here feel free to leave a comment and it will be added to the list!

W / A / S / D - Basic movement controls
Space - Ascend
Left Control - Descend

TAB - Inventory / Item List

• This menu serves as the only way to spawn blocks in the world
  
• On the right hand side there is a list of "palettes" to choose from, each one will change how the map blocks look, as well as what other props you have access to.
  
• You can mix and match props from different palettes, but will have to switch between them to choose each prop.

Left-click - Confirm placement
Right-click - Cancel placement
Middle-click (Mouse 3) - Duplicates the last block spawned
Q - Rotate counter-clockwise
E - Rotate clockwise

Left-click - Select block
Right-click - Deselect block
Delete - Removes block

Upon selecting a block:
Q / 1 - Move block

• Allows you to MOVE a block according to it's axis.
  
• Mouse over one of the arrows and drag to change the block's position.
  
• Tapping Left-Control will change the axis it's moved on. It will switch between the block's axis and the world's axis.

E / 2 - Rotate

• Allows you to ROTATE a block according to it's axis.
  
• Mouse over one of the rings and drag to change the block's rotation.
  
• Tapping Left-Control will change the axis it's moved on. It will switch between the block's axis and the world's axis.

R / 3 -Resize

• Allows you to RESIZE a block according to it's axis.
  
• Mouse over one of the colored blocks and drag to change the block's size.
  
• The size change will not retain it's original dimension ratio, instead it will stretch the block.
  
• Tapping Left-Control will change the axis it's moved on. It will switch between the block's axis and the world's axis.

F - Unlocks your mouse

• Pressing F again locks your mouse in place once more.
  
• This is the only way to access the Move Snap and Angle Snap options in the bottom right.
  
• If you select a block and then enter this mode, you can click anywhere on screen to begin creating a square. Click anywhere else again to select all blocks in the square. Entire sets of blocks can be moved, rotated, and deleted using this method.

Move Snap:
This menu in the bottom right will change the minimum number of units a block or prop will move. By default (or when this option is disabled) every block moves one unit at a time when moved. When using this setting make sure the option has a green check mark in it, or else all items will move one unit at a time.

Angle Snap:
The menu in the bottom right will change the minimum number of degrees a block or prop will rotate. By default (or when this option is disabled) every block moves one unit at a time when moved. When using this setting make sure the option has a green check mark in it, or else all items will rotate one degree at a time.

(Credit to the developers for this addition)
B - Creates the start position of the tracking shot

• This won't actually be the starting position of your tracking shot. Instead, the position of your camera will be used and then move on to the starting position.
  
• Along with waypoints, this will use both your camera's position and the direction your camera is looking to create the start point.

M - Starts the tracking shot.

• Pressing M again will prematurely end your tracking shot.
  
• Once you start a tracking shot, the points for it will dissapear and have to be put down again.

C - Slow down
V - Speed up

J - Toggles record menu

• I don't know much about this mode or how it works, more will be added later.
  
• Opening and closing this causes your mouse to become stuck, pressing F twice fixes this.

K - Toggles gamma

• Increases the brightness of the map, useful in the graveyard or mines setting, blinding on grasslands or icelands.

L - Toggles Flashlight
G - Toggles white auto-snap blocks
H - Toggles auto-snap
P / Escape - Opens pause menu
T - Highlights meshes

Testing:
If you want to test any hole that you've made, place a hole spawn on the course and right click on it. From here you can edit what hole it is and the par for that hole.
(Credit to the developers for this addition)