2 answers
There is a limit, but it's definitely not 10. I believe it is 500. If you use record types, when you add the values to the picklist, you also have to make them available to the record type you want them to be available in. I'm guessing you may have skipped this step. To add them after the fact, go in to Setup... Customize... Accounts... Record Types, and click on the Record Type where you want the values to display. Click the picklist field name, and move desired values from the Available Values box to the Selected Values box. Repeat this for any Record Type where you want them to be available.
