If you want to change this default maximum number of post, you will have to edit the template. First, backup your blog template (Dashboard > Template > Backup (at the top right corner) > Download full template > All files)
Now you got to open the template editor (Dashboard > Template > Edit HTML). Tick [ ] Expand Widget Templates
Now use ctrl+F to help you find the following codes:
Replace the above with the following (I used the number 150 because I want all posts to be displayed in the label page. You may use other numbers in place of 150):
Repeat this for all instances of that you can find. I think for the Simple template, there will be 3 instances, so the above will have to be repeated 3 times.
When done, save template and exit.