Register Sumatra in Windows 10


Thank you, administrator (and robot, of course, LOL), for admitting me to this forum. I’ll try to contribute with my knowledge whenever I know something as a fact or factual experience. However, I’m not systems savvy. Since Windows 10, with its new graphic user interface, I’m actually lost due to the “glitz and glamour” of the W10 tiles and new windows format which seems to me to be an attempt to imitate Android.

The program is very nice. It loads quickly and also displays quickly many PD files in one window. I have been using it for many years without difficulties on XP and W7 computers.

It also works on W10, but I don’t know how to make it the default program so that it starts up whenever I click on a PD file in Windows Explorer. I knew how to configure this on W7 starting at its Control Panel window.

I tried the same in W10, but the Control Panel “kicks” me into this new tile interface and windows display format. Sumatra is not listed in said windows as an option, neither does PDF appear.

Sumatra was installed directly through the FireFox browser as a 64-bit program on a Spanish language w10. Whenever I click on the Sumatra icon, it starts up and asks me in a small window whether I would like it to be my default reader. Of course, I do, but it does not register.

I hope that someone knows where and how I am going wrong.



welcome, you are not doing anything “wrong” it is Windows 10 constantly trying to redirect the default PDF reader to EDGE
I do not know Spanish language W10 the first place to try in English is “default app”



if that works for you please let us know


Thank you, it worked. Ingenious! I followed your instructions, looking up some words in the dictionary.

These are the steps in Spanish:
All the windows that pop up have a black, not white, background

  1. In the search box (of the looking glass): Aplicaciones predeterminadas
  2. An empty window pops up and after 10 seconds or so it fills up, similar to the first photo.
    Click on “Eligir aplicaciones predeterminadas por tipo de archivo”
  3. A similar, but different, empty window pops up which takes some time to fill, similar to the second photo above.
    With the “AvPág” (Page Down) key scroll to “.pdf”, just like above.
  4. Click on “Microsoft Edge” and a small (black) window pops up.
  5. Select SumatraPDF
  6. Leave the window
    It works, hurray!!!

The example helped me find my way through the “glitz and glamour” of W10 windows, especially those with a black background on a black desktop. It is difficult to see the boundaries. Also, I observed that text is often written in grey instead of black which makes it difficult to read.
I am wondering whether you too found the W10 style more difficult than W7, or whether is it just me since I am “tuned” to text and schematics, expecting clear boundaries.


Thanks for your explanation which may help other Spanish users

Your comments about colour suggest your app theme is set to dark rather than light

have you changed color settings ?


Yes, I did, and now I can see the three window’s icons on the top right.
In the image above, the right frame agreed with the one my computer shows, but the left frame had a different layout. Just to show that not every configuration must be the same.
Thanks for your help.