Grab
Mode
Edit Mode
Tool
Toolbar ‣ Grab
The Grab brush moves UVs around.
Brushes
The to select a preset brush type or a custom brush.
Radius
This option controls the radius of the brush, measured in pixels. F allows you to change the brush size interactively by dragging the mouse and then LMB. Typing a number then enter while using F allows you to enter the size numerically.
Strength
Controls how much each application of the brush affects the UVs. You can change the brush strength interactively by pressing Shift-F in the 3D Viewport and then moving the brush and then LMB. You can enter the size numerically also while in Shift-F sizing.
Use Unified Strength
Use the same brush Strength across all brushes.
Note
All brushes use the Airbrush Stroke Method; they continue to act as long as you keep LMB pressed.
Falloff
The Falloff allows you to control the Strength falloff of the brush. See for more information.
Reference
Edit Mode
Panel
Sidebar ‣ Tool ‣ Options
When UV sculpting is activated, the Sidebar shows the brush tool selection and options.
Lock Borders
Locks the boundary of UV islands from being affected by the brush. This is very useful to preserve the shape of UV islands.
Sculpt All Islands
To edit all islands and not only the island nearest to the brush center when the sculpt stroke was started.
Display Cursor
Hides the sculpt cursor.