In "settings> apps > acrobat" you can try to reset that setting and make it again. You can also restore all default open settings at settings> apps > top-right-menu .if that don't help try a factory reset*.
Please report if that helped you.
wipe data/factory reset in recovery (this will delete your data/settings):
- Power off and then press Power and Volume-up together for around 10 Seconds
- be sure that the little arrow point on recovery (select with volume up, enter with volume down)
- Then the open android with red triangle+"no command" is shown - press Power and Volume up together again
- Select Wipe data/factory reset with volume keys, confirm with power
- After factory reset select reboot system now