How do I change text orientation from RTL to LTR?

You can try this Adobe Photoshop CS4 - template to edit and create Arabic text, which should also work in Photoshop Elements. There are directions inside the dmg on how to use it.

http://download.adobe.com/pub/adobe/photoshop/mac/cs4/ArabicTemplate_PSCS4.dmg

Some things come to mind:

Your country region is not set correctly in your preference file.

The font

Or this: assuming it happens with all text in all apps:

• To change selected text: Click and drag to select the text. Press Control + Option + Command + Right Arrow.
• To change a paragraph: Place your cursor anywhere in the paragraph. Press Control + Command + Right Arrow. 

1. Click inside the paragraph with the reversed text.
2. In the menu bar, choose Format > Text (or Alignment in some apps).
3. Select the Left to Right or Default writing direction. The "Default" option will automatically set the direction based on the first character typed. 

1. Control-click (or right-click) the text with the reversed direction.
2. In the menu that appears, choose Writing Direction (or Paragraph Direction).
3. Select Left to Right or Default. 

1. Go to Apple menu > System Settings.
2. Click Keyboard in the sidebar.
3. Click Text Input, then click Edit.
4. If a right-to-left language like Hebrew or Arabic is listed, check that you are not accidentally switching to it. You can also review the keyboard shortcuts in this menu. 

Photoshop Elements doesn't have any settings for character direction.

You can try resetting the Type Tool by clicking on the three small dots at the far right of the tool options and then clicking Reset Tool.

If that doesn't work the next step would be to reset the Photoshop Elements Editor preferences by going to Adobe Photoshop Elements (your Version) Editor>Settings (or Preferences)>General, clicking Reset Preferences on next launch, then restarting the Adobe Photoshop Elements Editor.

Are you using Photoshop or Photoshop Elements?

What operating system?