Q: I've been using the free Adobe Acrobat Reader DC to fill-in and save PDF tax forms on my PC. But when I recently called up a stored tax form, the data I'd filled-in appeared for a moment, then disappeared, leaving just a blank tax form.

I then called up other tax forms that I'd saved earlier, and found that they still had their data. I then tried using another PC, and found that some stored tax forms contained the data I'd entered, while others had gone blank. Adobe won't help me with this problem because I'm using a free app. What's wrong and what can I do?

Mike Hess, Monument, Colo.

A: The disappearing tax data problem is caused by the way Adobe PDF files are stored.

When you look at a PDF file on your PC screen, it appears as one page after another as you scroll down.

But when a PDF file is stored, its contents are kept in layers of data so that the file will take up less space on a hard drive or other data storage device.

Occasionally this data layering has an unintended visual effect: When a PDF form is filled out, stored and then opened again, the information that was entered seems to have disappeared — even though it's still present.

The workaround for this problem is to "flatten" the PDF file, so that it stores all of its data in one layer instead of stacking one piece of information on top of another.

Once the layers are gone, you'll be able to see all the tax information you entered every time the PDF file is opened.

However, this workaround comes with a limitation: Once you've flattened a PDF file, you won't be able to add any more data to it, or to convert it back into a regular PDF file. So, make sure your tax form is complete and accurate before you make the change.

Here are two ways to turn your completed tax form from a normal PDF file into a flattened one:

• In the PDF file, press the CTRL and P keys simultaneously. You'll then see a box with choices for how to print the file; choose either Adobe PDF or Microsoft PDF as your "printer." In most cases, this will flatten the PDF file.

• In the PDF file, use the "save as" command to save the tax form as an Adobe PostScript file (which has the suffix ".ps").

Then use one of several free websites (see tinyurl.com/y9wkhh94 or tinyurl.com/dtb4sneb or tinyurl.com/48s65r7w) to convert the PostScript file into a flattened PDF file.

Q: I'm lefthanded. How can I change Windows 10 so that the vertical scroll bar in programs is on the left side of the screen instead of the right side?

Jim Pennington, Baldwin, Minn.

A: Microsoft doesn't allow you to move the scroll bar in Windows or in most of its programs. This lack of accommodation for lefthanders seems odd, since they make up 10% of the population. (The exception is Microsoft's note-taking program, called OneNote. To move its scroll bar from the right side of the screen to the left, see tinyurl.com/249m6wyd).

But some web browsers allow you to move the vertical scroll bar function (although not the scroll bar itself.) The free "ScrollAnywhere" extension for the Google Chrome (see tinyurl.com/3hr7hkke) or Mozilla Firefox (see tinyurl.com/ythmwee9) browsers lets you scroll from any point on a web page by holding down a mouse button. (To select which mouse button to use, click the program icon at the top right of the browser, then choose "options.")

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