You will find the Settings button at the bottom of the Help screen, or access by the Action Menu on the Document Preview Screen

Pre-Rendering Options

PDF Scale Factor: (2x) Performance versus visual accuracy

If you have very small typography or lines you may need to increase this.  People using aeronautical charts with very small print you might need to use a setting of 6x. 

Larger values require more memory, storage, and time to draw and time to generate the meta data, so you trade resolution for memory & drawing time. For most documents the default of 2x is acceptable. But maybe a setting of 0.24x or 6x is more applicable. 

This setting is not applicable to TIFF documents as they are pixel based.

After a document is processed you can use the action menu 'Re-PreRender" item to delete and recompute the meta-data. 

Fax Rescale Preview: (On) Rescale fax if viewing without pre-rendering

This option does not correct rectangular fax machine dots if you turn OFF Always Prerender.

Fax Rescale PreRendered: (On) Rescale fax when pre-rendering

You can choose to view a fax with square or rectangular dots. Using rectangular dots usually causes the view to appear distorted. 

Always PreRender: (On) Automatically pre-render files

When a fax document is imported, always process the fax to ensure a proper visual representation and to create a PDF. It is recommend to always leave this ON

Always Make PDF: (On) Automatically make PDF

When we pre-render the document, we also make a PDF representation if it is a TIFF document.

32-Bit Color for JPEG / PNG: (On) For true color

Generally, images are 32-bit color. If your image is black-and-white or mono consider turning this off to improve drawing performance and decrease storage needs.

32-Bit Color for TIFF / PDF: (Off) For true color

Generally, most TIFF documents are black-and-white. As are PDF documents. Therefore, we turn OFF 32-bit color. However, if you have a color TIFF or pictures in your PDF document, turn this ON if you see color banding in the page. 

Rendering Options

Smooth JPEG / PNG or Smooth TIFF / PDF: (On) For smooth pixels

The operating system will attempt to smooth pixels as you zoom in. How much zooming is allowed is determined by the Maximum Zoom setting.

Page Options

Scroll Vertically: (On) Scroll vertically

You can choose to view pages either left/right or up/down.

Scroll Bounces: (On) Scrolling bounce

This enables or disables Apple's scroll bouncing when scrolling to the top/end of a document.

Tap Areas For Scrolling: (On) Tap left/right or top/bottom of page to scroll

Depending if scrolling is vertical or horizontal, we enable/disable invisible tap areas to enable paging forward or back.

Scroll by Page: (On) Scroll by page

If this is off, the page to page scrolling is animated, versus jumping to the next page.

Directional Scroll Lock: (On) Restrict scrolling to initial direction

On a swipe or tap & move, the page is scrolled up/down or left/right. But it can scroll diagonally if the initial direction is not up/down/left/right.   

Scroll Lock is Hard: (On) Enforce directional scrolling

On a swipe or tap & move, the page is scrolled up/down or left/right based on the vertical or horizontal scrolling.  

Variable Page Size: (On) Better for variable page size faxes or scanned books with variable page sizes. 

More information here.

Bias by Height: (On) Resize by height.

The page is scaled to fit the height of the device. The entire width of the page may or may not be visible. 

Bias by Width: (On) Resize by width

The page is scaled to fit the width of the device. The entire height of the page may or may not be visible. 

★ Combinations of the above three settings will result in different looks and page handling. For example, if Bias Width & Height are both ON, we scale the page to fit the visual display area of the device.

Long Press for Nav Bar: (On) Show navigation bar on long press versus tap

If OFF, tapping will show the Navigation bar. If ON you have to tap/hold to show the bar.

Show Page Numbers: (On) Show page number

If ON we show a Page Number widget in the top left. 

Use Single Tile Rendering: (On) Use older rendering logic for pages larger than 16 mega-pixels

If your page is greater than 16 mega-pixels turning this ON will provide better visual drawing. However, the risk is that our app will terminate due to memory usage issues. We suggest you try it with a modest sized large sheet drawing to see if it makes any visual drawing difference.

Maximum Zoom: ## Maximum amount of zoom

Historically, this is 8x but can set from 1x to 16x. TIFF documents are pixel based so zooming in makes the dots bigger. For other image types & PDFs, how much pixelation happens is dependent on the document type, resolution, Scaling Factor and Smoothing settings.