Here’s the best way to select a chunk of text of any size, especially when that chunk of text is larger than what you can see on the screen at one time:
Click the mouse to set the insertion pointer wherever you want the block to start — the anchor point.
Insert the cursor at the front of the desired text.
Scroll through your document.
You must use the scroll bar or the mouse wheel to scroll through your document. If you use the cursor-movement keys, you reposition the insertion pointer, which isn’t what you want.
To mark the end of the block, press and hold the Shift key and click the mouse where you want the block to end.
The text from the insertion pointer to wherever you clicked the mouse is selected as a block.