I have downloaded some to the contest strategies and adding and changing the code to make some of the strategies that are worthy with less risk to run.

All strategies have different result for different time period that the tester can select from combo box beneath the instrument selection.

When I am running the strategy from Demo or live account for testing, I open the instrument chart and set it to specific time period.

I do not know if this is a correct way to select a default time period to run (local-run) a strategy.

How is this possible manually?
How is it possible through coding?

In the historical tester combo box, you should ONLY use "ticks", the other options are not to be trusted.

Thanks for the replay.
I am coming from MT4. An EA is design with specific time period in mind.
Some are good for 15 minutes and some must run under one hour, otherwise it will fail.
There is difference in each time frame trending, open and close bar, so based on these crucial elements your code and indictors are implemented, we have no choice but to run a Strategy for specific time frame.

In Jforex how can the user determine that?

This is a replay from SUpport:
The use of the period in the historical tester is crucial as any period other than ticks implies some interpolation. Interpolation might not be a good thing depending on what does the strategy.

Interpolation works in a way that if you have selected some interpolation period, the tester proces will take the close, open, high and low of the period step for processing the strategy. If the strategy has its core process onTick, however, the interpolation method for testing will return other results, most probably off. The greater the interpolation period step is, the greater the difference in results will be.

For the maximum precision in the testing mode, we encourage users to download the ticks for testing purposes.

Now, if the question is about designing a strategy according to a specific time frame, it is possible. The onBar interface is used generally with that purpose. Identification of the bar allows users to make the strategy working according to the set, or preferred period frame.