Hello, Bob.
I have a couple of reasons why the check number changes. I'll also throw some solutions to fix this.
Does it change whenever you enter a new check after saving the previous one? If so, the numbers follow a sequence and this changes on the next check.
If you need to reset or correct the sequence, you can do it by editing the Check no. box on the current or your next check.

If the number keeps changing right after saving the current check, then this might be a cache-related issue. Use a private or incognito window to confirm this:
- Google Chrome: Ctrl + Shift + N
- Mozilla Firefox: Ctrl + Shift + P
- Safari (new versions): Command + Option + P
Create a dummy check and observe the Check no. box. When it doesn't change, then go to the regular browser and clear the cache. Close it afterwards to finish the process. Alternatively, you can use another supported browser.
Need assistance after fixing the check number issue? Feel free to visit our articles for guides and tutorials.
Don't forget to jump into this thread again if you have more questions. I'm here to assist you in accomplishing your tasks.