Does anybody know how to add a location for sales tax? Every time I click add another location it won't let me switch states?

Edit the dates of the state you have entered from the summary screen.   If you have one state already entered for the full year (1/1 - 12/31), it won't allow another.   We need to know where you actually lived (not your state of residency) and your total sales tax rate. The total rate could include both state and local rates.   Do one entry at a time, starting with where you lived on Jan1.   TurboTax will ask you to verify the dates for each line item.

Moved within the Same State
If you moved within your state and each location has a different local sales tax rate, select the same state for each location. Also, enter the dates you lived in each location and the total state and local sales tax rate for those locations.

Moved to a Different State
If you moved to a different state, enter each state, the dates you resided there, and the total state and local sales tax rates.

Sales Tax Rate Changed During the Year
Enter the same location twice, once for each sales tax rate charged. Make sure to enter the dates you paid each rate.

You can add as many lines as you need, but the dates can't overlap.   You get the question about major purchases for each line item.   See example below - 4 states/4 rates.